1. 为什么你练得越狠，越容易失眠？健身过度与皮质醇的恶性循环
你是否曾有过这样的经历：明明白天在健身房挥洒了汗水，感觉身体被掏空，晚上却翻来覆去睡不着？第二天醒来，非但没有神清气爽，反而感觉更疲惫，肌肉酸痛也恢复得特别慢。你可能会困惑，不是说运动有助于睡眠吗？为什么我练得越狠，反而越容易失眠，甚至感到身心俱疲？
这背后的“罪魁祸首”，很可能就是一种叫做皮质醇的激素。当我们的健身强度超过了身体的承受能力，也就是我们常说的“过度训练”时，身体就会像拉响了警报一样，大量分泌皮质醇，试图应对这种“压力”。然而，这种“好心”的应激反应，却可能打乱我们身体原有的平衡，尤其是影响到至关重要的睡眠。
想象一下，你的身体里有一个精密的“总指挥部”，它负责调节各种生理功能，包括应对压力、管理能量，以及调控你的睡眠和清醒周期。这个“总指挥部”的核心，就是下丘脑-垂体-肾上腺轴（HPA轴）。平时，HPA轴就像一个称职的“管家”，在适当的时候释放适量的皮质醇，帮助你保持清醒和活力。比如，你早上起床时，皮质醇水平会自然升高，帮你启动新的一天。
但是，当你进行高强度训练时，HPA轴会把这视为一种巨大的“应激事件”。为了帮你应对这种“挑战”，它会火力全开，命令肾上腺大量分泌皮质醇。短期的皮质醇升高，确实能帮助身体调动能量，提高运动表现。但如果这种高强度训练持续时间过长，或者恢复不足，HPA轴就会长期处于“过劳”状态，导致皮质醇持续高位，节律紊乱 12。
这种长期高水平的皮质醇，就像一个不受控制的“压力警报”，它会持续地告诉你的身体“有危险”，让你时刻保持警惕，根本无法放松下来进入睡眠。更糟糕的是，皮质醇的升高还会反过来抑制褪黑素的分泌。褪黑素可是我们身体里的“助眠小精灵”，它负责告诉身体“该睡觉了”。皮质醇一捣乱，褪黑素就无法正常工作，你自然就难以入睡，或者睡不安稳 34。
于是，一个恶性循环就形成了：过度训练——皮质醇升高——睡眠紊乱——身体恢复更差——为了应对疲惫，身体进一步分泌皮质醇——更严重的失眠。长此以往，不仅健身效果大打折扣，你的身心健康也会受到严重影响 56。
所以，想要摆脱这种“越练越累，越练越失眠”的困境，我们必须先了解皮质醇这个“双面刃”，并学会如何与它和谐相处。
1.1 皮质醇的“应激警报”：过度训练如何触发HPA轴失控
我们前面提到，HPA轴是身体应对压力的“总指挥部”。当身体面临压力，比如高强度运动时，这个轴就会被激活，像多米诺骨牌一样传递信号：首先，下丘脑会释放促肾上腺皮质激素释放激素（CRH），CRH会刺激垂体分泌促肾上腺皮质激素（ACTH），最终ACTH会命令肾上腺释放皮质醇。皮质醇就是这样被生产出来的。
适量的皮质醇是好的，它能帮你调动储存的能量，提升注意力和反应速度，应对眼前的“挑战”。但问题出在“适量”二字。当健身强度过大，尤其是高强度的耐力训练（比如长时间跑步、骑行）或大负荷的力量训练时，身体会认为自己正处于一个非常大的“应激状态”。为了应对这种巨大的身体压力，HPA轴就会被过度刺激，持续不断地发出“警报”，导致皮质醇的分泌量大幅增加 7。
打个比方，正常训练时，HPA轴就像一个精准的“恒温器”，能根据身体需求调控皮质醇的水平。但过度训练时，这个“恒温器”就失灵了，皮质醇的分泌开关被卡在“开启”状态，长时间居高不下。研究发现，过度训练的运动员，他们的HPA轴功能会受到影响，例如对胰岛素引起的低血糖反应变弱，这表明下丘脑功能出现了问题 8。长期的高强度训练甚至可能导致慢性皮质醇水平升高，并影响其他激素的平衡，例如睾酮水平下降 910。
更糟糕的是，皮质醇的升高还会导致一个“恶性循环”。高水平的皮质醇会干扰大脑中调节睡眠的化学物质，让你难以入睡。而睡眠不足本身就是一种巨大的生理压力，它会反过来进一步刺激HPA轴，导致皮质醇分泌更多 11。也就是说，你越睡不着，皮质醇就越高；皮质醇越高，你就越难睡着。这就像一个滚雪球，让身体陷入“训练过度——皮质醇飙升——睡眠剥夺——皮质醇更高——更难恢复”的泥潭。
此外，长期过高的皮质醇还会打乱我们身体正常的皮质醇节律。健康的皮质醇分泌模式应该是早上醒来后达到高峰，然后逐渐下降，在夜间睡觉时达到最低点。但过度训练导致的皮质醇失衡，会让这个节律变得混乱，例如有些过度训练的运动员，他们的晨起皮质醇觉醒反应会降低 12。也就是说，你早上该有精神的时候可能精神不振，而晚上该睡觉的时候，皮质醇却可能依然高企，让你辗转反侧。
1.2 皮质醇飙升的身体信号：从失眠到恢复力下降的连锁反应
当身体长期处于高皮质醇状态时，它会向我们发出各种“求救信号”，告诉你需要调整了。这些信号不仅体现在睡眠上，还会影响到你的整体健康和恢复能力。
最直接、最让你困扰的，可能就是失眠。你可能会发现自己夜间容易清醒，睡着后一有风吹草动就醒来，或者半夜醒来后就再也睡不着。即使一晚上都在床上，第二天醒来却感到晨醒疲惫，好像根本没睡一样，甚至比没运动时更累。这是因为皮质醇长期高位，就像一个不知疲倦的“守夜人”，它会持续刺激你的中枢神经系统，让大脑保持兴奋和警觉，即使你身体已经很累了，大脑却停不下来。
除了失眠和疲惫，你可能还会注意到身体的恢复力明显下降。平时健身后一两天就能恢复的肌肉酸痛，现在可能需要三四天甚至更久。训练表现也可能停滞不前，甚至开始下降，力量和耐力都大不如前。这又是皮质醇在“捣鬼”：高水平的皮质醇会分解蛋白质，减缓肌肉修复和生长。它还会抑制免疫系统，让你更容易生病，恢复起来也更慢 13。想象一下，如果一个工人白天辛苦工作，晚上却得不到充分休息和营养补给，第二天他怎么可能有精神和力气继续工作呢？身体恢复也是同样的道理。
更深层次地看，皮质醇飙升对睡眠的破坏机制是多方面的。它不仅直接让大脑保持警觉，更重要的是，它会抑制褪黑素的分泌。褪黑素是我们身体里非常重要的“睡眠信号员”，它像一个生物钟，在天黑后告诉身体“该准备睡觉了”，帮助我们进入并维持睡眠。但高水平的皮质醇会干扰褪黑素的正常分泌节律，就像皮质醇这个“兴奋剂”把褪黑素这个“安眠药”的效果抵消了一样。结果就是，你晚上该分泌褪黑素的时候，分泌量却不足，自然就难以入睡或深度睡眠不足。
长期高皮质醇还会破坏我们的深度睡眠。深度睡眠，也叫慢波睡眠，是身体和大脑进行修复和恢复最重要的阶段。在这个阶段，生长激素大量分泌，帮助肌肉修复，免疫系统也会得到强化，大脑会清除代谢废物，巩固记忆。但皮质醇的干扰，会导致深度睡眠时间缩短，质量下降 14。这就像你的身体虽然“睡着了”，但并没有真正进入“深度维护模式”，修复效果大打折扣。
于是，一个环环相扣的恶性循环就形成了：
- 训练过度：你为了追求更好的健身效果，不断提高训练强度和频率。
- 压力飙升：身体将这种过度训练视为巨大压力，HPA轴被过度激活，皮质醇开始大量分泌。
- 失眠来袭：高皮质醇抑制褪黑素，破坏深度睡眠，导致你难以入睡、夜间易醒、晨起疲惫。
- 身体更疲惫：睡眠不足和高皮质醇共同作用，让肌肉恢复变慢，免疫力下降，你感到比平时更累，训练表现也开始下滑。
- 陷入泥潭：为了应对这种疲惫和不佳的表现，你可能会更努力地训练（或者产生更大的心理压力），从而进一步刺激皮质醇分泌，加重失眠和疲惫，陷入一个“训练-压力-失眠-更疲惫”的恶性循环。
所以，当你出现失眠、恢复慢、精神不济这些信号时，是时候停下来，听听身体的声音了。这不仅仅是健身效果的问题，更是关乎你整体健康和生活质量的大事。
2. 训练调整第一步：从“拼命练”到“聪明练”的3个关键
既然我们已经明白了过度训练和皮质醇飙升之间的“爱恨情仇”，那么解决问题的第一步，就是调整我们的训练策略。这不是让你放弃健身，而是要从“拼命练”的误区中走出来，转变为“聪明练”，让身体在获得锻炼益处的同时，也能得到充分的休息和恢复。
简单来说，“聪明练”就是：了解身体的承受能力，合理安排训练强度和频率，并学会倾听身体的反馈。这就像给你的健身计划安装一个“智能调控系统”，而不是一味地猛踩油门。
2.1 强度控制：如何用“阶梯式负荷”替代“暴力突破”
很多健身爱好者，尤其是新手，总觉得训练强度越大、越累，效果就越好。他们常常追求每次训练都力竭，甚至挑战极限。殊不知，这种“暴力突破”式的训练方式，正是导致皮质醇飙升的元凶之一。研究表明，中高强度的运动才会显著提高血液中的皮质醇水平 7。
想象一下，你的身体就像一个弹簧，每次训练都在给它施压。如果压力适中，弹簧会变得更有弹性。但如果每次都把弹簧拉到极限，甚至超过极限，那它迟早会变形，甚至断裂。皮质醇的反应也是一样。
那么，如何避免这种“暴力突破”呢？答案是采用“阶梯式负荷”的训练原则。
1. 分散大强度训练，每周不超过2次：
这就像盖房子不能一次性把所有重活都做完。你的身体需要时间来适应和修复。如果你习惯每周进行3-4次，甚至更多次高强度训练，比如大重量深蹲、硬拉，或者高强度间歇训练（HIIT），那么是时候重新审视了。高强度训练对身体的刺激巨大，会显著升高皮质醇 7。因此，建议将真正意义上的“大强度”训练（比如达到力竭或接近力竭的训练），分散到每周不超过2次。这能给你的HPA轴喘息的机会，不让它长期处于“应激警报”状态。当然，对于一些特殊人群，比如中风康复患者，高强度训练可以改善下肢功能，但对于一般人来说，我们需要更谨慎地控制强度 1516。
2. 引入低强度有氧，给身体“降降火”：
高强度训练是“火”，低强度有氧就是“水”。适量的“水”可以帮助身体“降降火”，让皮质醇水平回落。研究发现，低强度运动并不会显著升高皮质醇水平，甚至在调整了血容量和昼夜节律后，低强度运动还能略微降低皮质醇水平 7。
所以，在你的训练计划中，可以加入一些低强度的有氧运动，例如：
- 快走（Brisk Walking）：这是最简单也最有效的低强度有氧运动。每天30-45分钟的快走，不仅能促进血液循环，帮助身体排出代谢废物，还能有效缓解精神压力。
- 游泳：水的浮力可以减轻关节负担，同时提供全身性的有氧锻炼，帮助放松身心。
- 轻松骑行：无论是户外骑行还是室内单车，保持一个能轻松交谈的强度，都是很好的低强度有氧选择。
这些低强度有氧运动，不仅不会过度刺激皮质醇分泌，反而能帮助身体更好地恢复。它们就像是训练计划中的“缓冲垫”，让你的身体在紧张和放松之间找到平衡。记住，健身不只是追求肌肉的增长和力量的提升，更重要的是身体整体的健康和平衡。学会控制强度，才能让你的健身之路走得更远，更健康。
2.2 频率优化：给身体留足“修复窗口”的训练周期设计
除了控制每次训练的强度，训练的频率同样是影响皮质醇水平的关键因素。如果你每天都在高强度训练，身体根本没有足够的时间来修复和恢复，皮质醇自然会持续居高不下，无法回落到正常水平。这就好比你给汽车加足了油门，却不给它停车休息的时间，再好的车也得报废。
研究发现，过度训练的一个典型表现就是皮质醇持续升高，无法在训练间歇回落到基线水平 17。这意味着身体长期处于一种应激状态，无法有效进行修复。因此，优化训练频率，给身体留足“修复窗口”，是降低皮质醇、改善睡眠和恢复力的重要策略。
以下是一些具体的实践建议：
1. 力量训练：间隔至少48小时
力量训练对肌肉纤维的刺激较大，需要较长时间才能完全恢复。一般而言，针对同一肌群的力量训练，建议间隔至少48小时。这意味着如果你周一练胸，周三或周四再练胸会更合适，而不是周二就再次轰炸同一块肌肉。
例如：
- 全身训练（Full Body Workout）：如果你采用全身训练模式，可以安排每周2-3次，每次训练之间至少间隔一天休息。
- 分化训练（Split Routine）：如果你将训练部位进行分化，例如“胸部+三头肌”、“背部+二头肌”、“腿部+肩部”，那么确保每个肌群在下一次训练前有充分的休息。
2. 耐力训练：每日不超过90分钟
对于长距离跑、马拉松训练等耐力项目，长时间的持续运动同样会对身体产生巨大压力。虽然低强度有氧运动对皮质醇的影响较小，但长时间的耐力训练，尤其是中高强度下的长时间训练，仍可能导致皮质醇升高。
建议耐力训练，尤其是中高强度的耐力训练，每日单次时长控制在90分钟以内。如果你需要进行更长时间的耐力活动，可以考虑将其拆分成两次短时训练，并确保中间有充足的休息和能量补充。
3. 加入主动恢复日：瑜伽、拉伸或轻松散步
“休息”不等于“什么都不做”。在训练日之间安排主动恢复日，能帮助身体更好地恢复，同时促进血液循环，缓解肌肉僵硬。主动恢复通常指低强度、温和的运动，不会给身体带来额外压力，反而有助于放松身心。
- 瑜伽或普拉提：这些运动注重呼吸和身体的柔韧性、核心力量，能有效放松紧张的肌肉，改善身体姿态，同时也能起到很好的精神放松效果，帮助降低皮质醇。
- 全身拉伸（Stretching）：在休息日进行全身性的拉伸，尤其是针对平时训练较多的肌群，能增加肌肉弹性，减少运动后的延迟性肌肉酸痛（DOMS），加速恢复。
- 轻松散步或慢跑：在环境优美的户外进行30-60分钟的轻松散步或慢跑，不仅能呼吸新鲜空气，也能让身心得到放松，有助于调节情绪和降低皮质醇。
通过优化训练频率，确保每个肌群、每个系统都有足够的“修复窗口”，你可以有效避免皮质醇的长期高位，让身体在更健康、更高效的状态下不断进步。记住，健身是一场马拉松，而不是百米冲刺，长期的坚持和合理的规划才是制胜之道。
2.3 监测指标：用“身体反馈”代替“计划执念”的科学调整法
我们常常会制定周密的训练计划，但这计划毕竟是基于理想状态。身体不是机器，它每天的状态都可能不同。如果一味地坚持计划，而忽视身体发出的信号，很可能会陷入过度训练的陷阱。因此，学会“倾听”身体的反馈，并根据这些信号灵活调整训练，才是真正的“聪明练”。
这里有几种简单易行的方法，可以帮助你监测身体的恢复状态，及时发现皮质醇飙升的苗头：
1. 晨起静息心率：身体的“晴雨表”
你的静息心率（Resting Heart Rate, RHR）就像是身体的一面镜子，能反映出你的自主神经系统（控制心跳、呼吸等无意识功能的系统）的活跃程度。一般而言，健康的成年人静息心率在60-100次/分钟之间。
- 测量方法：每天早上醒来，在下床前，保持平躺状态，测量1分钟的脉搏。最好连续几天测量，取平均值，建立你的“基线静息心率”。
- 信号解读：如果你的晨起静息心率持续升高（比平时基线高5-10次/分钟，并持续2-3天）18，这可能预示着身体还没有从上次训练中完全恢复，自主神经系统处于过度兴奋状态，暗示皮质醇水平可能偏高。这时候，你的身体在告诉你：“嘿，我还没准备好，需要更多休息！”
2. 主观疲劳评分（Perceived Exertion Scale）：最直接的身体感受
没有任何仪器比你自己的身体感受更直接。主观疲劳评分就是让你给自己当前的疲劳程度打分，这是一个简单但非常有效的指标。
- 测量方法：每天醒来后，或者在训练前，问问自己：“今天感觉累吗？”用一个0-10的量表来评价：
- 0：完全不累，精力充沛
- 1-3：轻微疲劳
- 4-6：中度疲劳，影响日常活动
- 7-9：严重疲劳，不想动
- 10：极度疲劳，无法忍受
- 信号解读：如果连续几天你的主观疲劳评分都偏高（例如达到5分以上），并且伴随着肌肉酸痛恢复缓慢、缺乏训练动力等情况，这很可能是过度训练的信号。研究表明，疲劳程度与体能恢复、甚至某些神经生理指标都有关联 1920。
3. 睡眠质量记录：皮质醇最明显的“受害者”
睡眠是身体恢复和调节激素最重要的时段。皮质醇飙升最明显的表现之一就是睡眠问题。记录你的睡眠质量，能帮你发现潜在的问题。
- 测量方法：你可以使用智能穿戴设备（如运动手环、智能手表）来监测你的睡眠时长、深度睡眠比例、夜间醒来次数等。如果没有设备，也可以每天早上简单记录前一晚的睡眠情况：
- 入睡花了多久？
- 夜间醒来几次？每次醒来多长时间？
- 早上醒来感觉精神如何？
- 总睡眠时长是多少？
- 信号解读：如果你的静息心率持续升高，或者连续3天睡眠时长不足6小时，并且感觉睡眠质量很差（频繁醒来，深度睡眠不足），这强烈表明你的身体处于恢复不足状态，皮质醇很可能过高。此时，继续高强度训练只会适得其反。
当身体发出“预警”信号时，你该怎么办？
一旦你通过上述指标发现身体亮起了红灯，就应该立即采取行动，而不是硬着头皮坚持训练计划：
- 降低训练强度和量：可以减少训练组数、次数，或者降低负重，将高强度训练替换成低强度有氧或主动恢复。
- 增加休息天数：给身体更多完全休息的时间，让HPA轴有机会“冷静下来”。
- 优先保证睡眠：比任何训练都更重要的是保证充足的睡眠。
- 调整饮食：确保摄入足够的能量和宏量营养素，支持身体恢复。
记住，训练计划是为了帮助你达到目标，而不是束缚你。灵活地根据身体反馈调整计划，才能让你的训练更科学、更有效，避免陷入皮质醇飙升的恶性循环。学会倾听身体的声音，它比任何教练都更了解你。
3. 吃对营养素：用饮食给皮质醇“踩刹车”
在了解了如何通过调整训练来控制皮质醇后，我们还要知道，餐桌上的“学问”也同样重要。我们的身体每天都在进行着复杂的生化反应，这些反应离不开各种营养素的参与。通过聪明的饮食选择，我们可以为身体提供“减压”所需的工具，帮助皮质醇“踩刹车”，让它在需要的时候升高，在不需要的时候乖乖降下来。
3.1 镁元素：天然的“压力缓冲剂”如何改善睡眠
你是否知道，有一种矿物质，它被称为“天然的镇静剂”，对缓解压力、改善睡眠有着意想不到的效果？它就是——镁元素。
镁在人体内扮演着极其重要的角色，它参与了300多种酶的反应，对能量代谢、肌肉收缩、蛋白质合成、DNA合成以及神经信号传递都至关重要 21。当身体长期处于高压状态，或者过度训练时，体内的镁消耗会增加，从而导致镁缺乏。而镁缺乏反过来又会加重身体的压力反应，甚至可能导致焦虑和HPA轴功能紊乱 22。这就像一个恶性循环，压力越大越缺镁，越缺镁压力越大。
那么，镁是如何帮助我们“踩刹车”、改善睡眠的呢？
- 调节HPA轴，降低皮质醇：研究发现，补充镁可以帮助调节HPA轴的过度活跃，从而降低血清皮质醇的浓度 232425。当皮质醇这个“兴奋剂”的水平下降，身体就能更好地放松下来，为睡眠做好准备。
- 促进褪黑素分泌：前面我们提到，皮质醇会抑制褪黑素的分泌。而镁元素不仅能直接降低皮质醇，还可以帮助提高褪黑素的水平，这个“助眠小精灵”的分泌量增加了，自然更容易入睡 2325。
- 镇静神经，改善睡眠结构：镁是天然的N-甲基-D-天冬氨酸（NMDA）受体拮抗剂和GABA（γ-氨基丁酸）激动剂。NMDA受体与神经兴奋性有关，而GABA是一种重要的抑制性神经递质，它能帮助大脑平静下来。通过调节这些神经递质系统，镁可以减少神经兴奋，增加慢波睡眠（也就是深度睡眠）的时间和效率，减少夜间醒来的次数，从而改善整体睡眠质量 2526。
- 缓解肌肉紧张和疼痛：研究表明，镁缺乏与肌肉疼痛有关 27。
多项研究都证实了镁补充剂对改善睡眠的积极作用。一项针对糖尿病患者的研究发现，补充镁可以显著降低皮质醇水平，提高褪黑素水平，并改善失眠的严重程度和睡眠时长 23。另一项针对老年人的研究也表明，镁补充剂可以缩短入睡时间，提高睡眠效率，减少早醒，并降低皮质醇水平 2528。甚至有研究发现，镁对中度压力的纤维肌痛患者有缓解作用，并能减轻疼痛感 29。
如何补充镁？
虽然市面上有很多镁补充剂，但我们更推荐从食物中获取，天然、安全且能协同吸收其他营养素。
推荐每日摄入量：镁的推荐摄入量因年龄和性别而异，通常成年男性每日推荐摄入量约为400-420毫克，女性约为310-320毫克。如果你是健身人群，或者处于压力较大的状态，可能需要稍高一些。
富含镁的食物来源：
- 绿叶蔬菜：菠菜、羽衣甘蓝、甜菜叶等深绿色蔬菜是镁的极佳来源。
- 坚果和种子：南瓜籽、奇亚籽、杏仁、腰果等都含有丰富的镁。其中，南瓜籽的含镁量尤其突出。
- 全谷物：糙米、燕麦、全麦面包等未经精加工的谷物。
- 豆类：黑豆、扁豆、鹰嘴豆等。
- 黑巧克力：可可含量越高，镁含量越丰富。
- 牛油果、香蕉等水果也含有一定量的镁。
不过需要注意的是，镁虽然好，但过量摄入也可能引起不适，例如腹泻。因此，在考虑使用补充剂前，最好先咨询医生或营养师的建议。通过均衡饮食，多摄入富含镁的食物，才是最健康、最可持续的补充方式。
3.2 肌酸与益生菌：从大脑到肠道的压力调节组合
当我们谈到对抗压力和改善睡眠时，除了镁元素这个“镇静剂”，还有两个“搭档”值得关注：它们就是肌酸和益生菌。一个从“大脑”着手，保护我们的中枢神经系统；一个从“肠道”发力，调节与情绪和睡眠息息相关的“第二大脑”。两者的结合，能为我们提供一套从内到外的压力调节方案。
肌酸：大脑的“能量保护伞”
你可能只知道肌酸是健身增肌的“神器”，能提高运动表现。但肌酸的作用远不止于此，它对大脑健康和情绪调节同样重要。
1. 保护大脑功能，应对压力损害：
肌酸在大脑中主要以磷酸肌酸的形式存在，为神经细胞提供快速能量储备。当身体和大脑承受巨大压力时，比如过度训练或精神压力过大，大脑中的能量代谢会受到影响，神经递质平衡也可能被打破。研究发现，在经历单一延长应激（一种模拟创伤后应激障碍的压力模型）后，大鼠前额叶皮质中的谷氨酸、谷氨酰胺和肌酸浓度会下降 31。而前额叶皮质恰恰是负责情绪调节、决策和认知功能的关键区域。这意味着，压力会消耗大脑的肌酸储备，进而影响大脑的正常运作。一项研究表明，复合了多巴胺D2受体部分激动剂和特定血清素再摄取抑制剂的SONU20176289化合物，能够防止慢性应激引起的大鼠前额叶皮层N-乙酰天冬氨酸、总肌酸和胆碱化合物的脑内浓度降低，并改善神经可塑性，提示组合多巴胺D2受体激动剂与SSRI活性可能是治疗抑郁/焦虑综合征的有效工具 32。此外，有研究指出，应激引起的肌酸-磷酸肌酸循环紊乱可能导致氧化损伤 33。
2. 改善认知，间接缓解压力：
当大脑功能受损时，我们可能会感到注意力不集中、反应迟钝，这本身又会增加我们的精神压力。肌酸可以通过提高大脑能量效率，改善认知功能，比如提升决策能力和短期记忆 34。虽然这不能直接降低皮质醇，但一个运转高效的大脑，能更好地处理信息，应对挑战，从而减少不必要的焦虑和压力。
3. 对抗氧化应激，维护神经元健康：
长期高皮质醇和压力状态会产生过多的自由基，导致氧化应激，损伤神经元。肌酸被认为可能通过调节能量代谢来间接减少氧化应激，例如，有研究表明，抗精神病药物可能通过增加肌酸水平来部分恢复应激引起的缺陷，从而对抗应激诱导的氧化损伤 33。这就像给大脑的“发电厂”加了一层保护膜，让它在压力下也能稳定运行。
益生菌：肠道-脑轴的“平衡大师”
近年来，“肠道-脑轴”的概念越来越受到关注，它揭示了肠道微生物群与大脑功能之间密不可分的联系。肠道不仅是消化器官，更被称为“第二大脑”，它通过神经、内分泌和免疫系统与大脑进行双向沟通，影响我们的情绪、认知和睡眠 35 36。
1. 调节肠道-脑轴，改善情绪和压力：
肠道菌群失衡（肠道菌群紊乱）已被证实与多种精神疾病有关，包括抑郁症和焦虑症 35 37。益生菌，作为对宿主有益的活性微生物，可以通过调节肠道菌群的组成和功能，影响肠道-脑轴的信号传递。它们可以产生短链脂肪酸（如丁酸），促进神经递质（如血清素）的合成，甚至调节炎症反应 35。这些作用都有助于改善情绪状态，降低焦虑和压力水平。
例如，一项针对羽毛球运动员的研究发现，连续六周补充益生菌，可以显著降低他们的焦虑和压力水平 38。另一项研究也表明，益生菌补充剂能够改善抑郁症患者的认知功能，并降低犬尿氨酸浓度 39。当压力和焦虑得到缓解时， HPA轴的过度活跃状态也会随之平息，从而间接降低皮质醇水平。
2. 改善睡眠质量：
既然肠道微生物能影响情绪，那它们对睡眠的影响也就不言而喻了。益生菌通过肠道-脑轴的调节，可以帮助稳定睡眠-觉醒周期，减少失眠和睡眠障碍 36 40。一些研究还表明，特定的益生菌菌株可能有助于改善睡眠潜伏期（入睡时间）和睡眠效率 40。
3. 增强免疫，辅助恢复：
过度训练和高皮质醇都会削弱免疫系统。益生菌能够增强肠道屏障功能，减少有害物质进入血液，从而提升免疫力 41 42。一个健康的免疫系统意味着更快的身体恢复，减少疾病风险，这也有助于减轻身体的整体压力。
如何补充肌酸和益生菌？
肌酸：
- 推荐摄入量：对于健身人群，通常建议每日补充3-5克肌酸。为了达到更好的效果，可以采用冲击期（每日20克，持续5-7天）后转维持期，或者直接每日稳定补充3-5克 43。
- 服用方式：肌酸可以随餐服用，或者在训练前后补充。由于它对认知功能也有益处，可以考虑在需要集中注意力的时段服用。
- 注意事项：确保选择纯度高的肌酸一水化合物（Creatine Monohydrate）。补充肌酸期间需要多饮水，以帮助肾脏代谢。
益生菌：
- 推荐摄入量：益生菌的有效剂量因菌株而异，通常建议每日摄入至少10亿（10^9）CFU（菌落形成单位）的益生菌。
- 食物来源：
- 发酵食品：无糖酸奶、开菲尔、泡菜、纳豆、味噌等都是益生菌的良好来源。优先选择含有乳杆菌（Lactobacillus）和双歧杆菌（Bifidobacterium）的发酵食品。
- 益生菌补充剂：如果通过饮食难以摄取足够，可以选择益生菌补充剂。建议选择含有多种菌株、CFU数量较高且经过科学验证的品牌。
- 服用方式：益生菌最好在饭前或饭后服用，以避免胃酸对其活性的影响。部分益生菌菌株需要配合益生元（Prebiotics，如膳食纤维）一起服用，效果更佳，益生元是益生菌的“食物”。
- 注意事项：选择适合自己的菌株，不同菌株有不同的功效。长期服用益生菌可能需要医生或营养师指导。研究显示，益生菌补充剂对于缓解疲劳有益，特别是连续补充至少28天，且每日剂量不低于150亿CFU的方案效果更明显 42。
将肌酸和益生菌纳入你的日常饮食和补充计划，不仅能为你的健身表现添砖加瓦，更能从大脑和肠道两个层面，为你的身体和心理健康提供强有力的支持，帮助你更好地管理压力，降低皮质醇，从而拥有更优质的睡眠。
益生菌：肠道-脑轴的“平衡大师”
近年来，“肠道-脑轴”的概念越来越受到关注，它揭示了肠道微生物群与大脑功能之间密不可分的联系。肠道不仅是消化器官，更被称为“第二大脑”，它通过神经、内分泌和免疫系统与大脑进行双向沟通，影响我们的情绪、认知和睡眠 4445。
1. 调节肠道-脑轴，改善情绪和压力：
肠道菌群失衡（肠道菌群紊乱）已被证实与多种精神疾病有关，包括抑郁症和焦虑症 444546。益生菌，作为对宿主有益的活性微生物，可以通过调节肠道菌群的组成和功能，影响肠道-脑轴的信号传递。它们可以产生短链脂肪酸（如丁酸），促进神经递质（如血清素）的合成，甚至调节炎症反应 47。这些作用都有助于改善情绪状态，降低焦虑和压力水平 4849。
例如，一项针对运动员的研究发现，连续补充益生菌，可以显著降低他们的焦虑和压力水平 42。另一项研究也表明，益生菌补充剂能够改善成年人的认知功能 48。当压力和焦虑得到缓解时， HPA轴的过度活跃状态也会随之平息，从而间接降低皮质醇水平 465051。
2. 改善睡眠质量：
既然肠道微生物能影响情绪，那它们对睡眠的影响也就不言而喻了。益生菌通过肠道-脑轴的调节，可以帮助稳定睡眠-觉醒周期，减少失眠和睡眠障碍 49。一些研究还表明，特定的益生菌菌株可能有助于改善睡眠潜伏期（入睡时间）和睡眠效率 4952。
3. 增强免疫，辅助恢复：
过度训练和高皮质醇都会削弱免疫系统。益生菌能够增强肠道屏障功能，减少有害物质进入血液，从而提升免疫力 424753。一个健康的免疫系统意味着更快的身体恢复，减少疾病风险，这也有助于减轻身体的整体压力。
如何补充肌酸和益生菌？
肌酸：
- 推荐摄入量：对于健身人群，通常建议每日补充3-5克肌酸。为了达到更好的效果，可以采用冲击期（每日20克，持续5-7天）后转维持期，或者直接每日稳定补充3-5克。
- 服用方式：肌酸可以随餐服用，或者在训练前后补充。由于它对认知功能也有益处，可以考虑在需要集中注意力的时段服用。
- 注意事项：确保选择纯度高的肌酸一水化合物（Creatine Monohydrate）。补充肌酸期间需要多饮水，以帮助肾脏代谢。
益生菌：
- 推荐摄入量：益生菌的有效剂量因菌株而异，通常建议每日摄入至少10亿（10^9）CFU（菌落形成单位）的益生菌。
- 食物来源：
- 发酵食品：无糖酸奶、开菲尔、泡菜、纳豆、味噌等都是益生菌的良好来源。例如，发酵食品中常见的乳杆菌（Lactobacillus）已被研究其在益生菌制剂中的应用潜力 54。
- 益生菌补充剂：如果通过饮食难以摄取足够，可以选择益生菌补充剂。建议选择含有多种菌株、CFU数量较高且经过科学验证的品牌。
- 服用方式：益生菌最好在饭前或饭后服用，以避免胃酸对其活性的影响。部分益生菌菌株需要配合益生元（Prebiotics，如膳食纤维）一起服用，效果更佳，益生元是益生菌的“食物”。
- 注意事项：选择适合自己的菌株，不同菌株有不同的功效。长期服用益生菌可能需要医生或营养师指导。研究显示，益生菌补充剂对于缓解疲劳有益，特别是连续补充至少28天，且每日剂量不低于150亿CFU的方案效果更明显 42。
将肌酸和益生菌纳入你的日常饮食和补充计划，不仅能为你的健身表现添砖加瓦，更能从大脑和肠道两个层面，为你的身体和心理健康提供强有力的支持，帮助你更好地管理压力，降低皮质醇，从而拥有更优质的睡眠。
3.3 晚餐策略：避免“燃料不足”与“消化负担”的双重陷阱
辛苦训练了一天，晚上吃什么、怎么吃，对于你身体的恢复、皮质醇的调节以及最终的睡眠质量，都起着至关重要的作用。一顿不合适的晚餐，可能让你陷入“燃料不足”和“消化负担”的双重陷阱，从而进一步推高皮质醇，影响睡眠。
想象一下，你的身体就像一辆汽车。白天运动消耗了大量“燃料”（能量），晚上需要“加油”才能修复和恢复。如果晚餐吃得太少，身体就会处于低能量可用性（Low Energy Availability, LEA）状态。这就像汽车油箱空了，身体会把这当成一种“饥荒”信号，激活HPA轴，让皮质醇升高，试图分解肌肉来获取能量 55。这种长期的低能量可用性，不仅会升高皮质醇，还会影响免疫系统，降低运动表现，甚至在补充能量后，这种负面影响还会持续 5556。所以，晚餐不能吃太少。
但如果晚餐吃得太多，尤其是高脂肪、高蛋白的食物，又会给消化系统带来巨大负担。在睡眠时，身体的各项机能都会放缓，消化系统也不例外。如果睡前大鱼大肉，胃肠道需要加班加点工作，这本身就会产生一种“压力”，影响身体进入放松状态，进而干扰睡眠。此外，夜间摄入过多的碳水化合物和蛋白质，可能会影响胰岛素敏感性，导致血糖波动，这同样不利于睡眠和激素平衡 57585960616263。
那么，怎样才能吃一顿既能补充能量、促进恢复，又不会造成消化负担，并且有助于降低皮质醇、改善睡眠的晚餐呢？关键在于“均衡”和“时机”。
晚餐的“黄金法则”：优质蛋白+慢碳+膳食纤维，热量占比30%-35%
1. 优质蛋白：修复肌肉，稳定血糖
蛋白质是肌肉修复和生长的基石。晚餐摄入适量的优质蛋白，能为身体提供足够的氨基酸，帮助修复白天训练造成的肌肉损伤，同时也能增加饱腹感，避免夜间饥饿。
- 选择：推荐选择消化负担较小、脂肪含量低的优质蛋白，如鸡胸肉、鱼肉（尤其是富含Omega-3的深海鱼）、虾、鸡蛋、豆制品（如豆腐）。
- 好处：
- 提供肌肉修复所需的“建筑材料”。
- 蛋白质的消化吸收相对缓慢，有助于稳定血糖，避免胰岛素飙升，从而减少皮质醇的波动。
2. 慢速碳水化合物（慢碳）：缓慢释放能量，提供助眠原料
碳水化合物对睡眠有着重要的影响。大脑正常运作需要葡萄糖作为能量。晚餐摄入适量的慢碳，可以持续稳定地为大脑提供能量，避免夜间血糖过低导致身体“报警”分泌皮质醇。同时，慢碳还能促进色氨酸进入大脑，色氨酸是合成血清素和褪黑素的重要前体，有助于促进睡眠。
- 选择：推荐选择燕麦、糙米、全麦面包、红薯、玉米、藜麦等复合碳水化合物。避免精米白面和高糖食物，它们会导致血糖快速升高，然后再快速下降，不利于睡眠。
- 好处：
- 缓慢释放能量，避免血糖剧烈波动，维持身体能量稳定，避免HPA轴被激活。
- 促进色氨酸转化为褪黑素，帮助身体进入睡眠状态。
3. 膳食纤维：促进消化，增加饱腹感
膳食纤维在晚餐中扮演着“润滑剂”和“饱腹感制造者”的角色。
- 选择：西兰花、菠菜、各种绿叶蔬菜、菌菇类都是极佳的膳食纤维来源。
- 好处：
- 增加饱腹感，让你不容易在睡前进食，减少消化负担。
- 促进肠道蠕动，保持肠道健康，间接有助于肠道-脑轴的健康，从而影响情绪和睡眠。
4. 晚餐热量占比：30%-35%
一天的总热量摄入中，晚餐的热量占比建议控制在30%-35%。这意味着晚餐不应该吃得过饱，但也不能过少。具体的摄入量要根据你的训练强度、体重和个人代谢情况来调整。
小贴士：
- 晚餐时间：尽量在睡前2-3小时完成晚餐，给身体留出足够的消化时间。
- 避免超加工食品（UPFs）：有研究发现，即使是适度摄入超加工食品也与皮质醇水平升高有关 64。这些食品通常含有高糖、高盐、高脂肪，且营养价值低，应尽量避免。
- 个性化调整：每个人的身体反应不同，上述只是一般性建议。你需要根据自己的身体感受和睡眠状况，进行个性化调整。如果你发现某种食物会让你睡不好，那就暂时避开。
通过优化晚餐结构，避免“燃料不足”和“消化负担”的双重陷阱，你可以更好地支持身体的恢复过程，降低皮质醇，为一夜好眠打下坚实的基础。
4. 重建睡眠节律：从“躺不平”到“深度修复”的环境与习惯
我们已经了解到，过度训练、营养不均会推高皮质醇，从而扰乱睡眠。但除了身体内部的化学反应，我们所处的环境和日常习惯，同样对睡眠质量有着举足轻重的影响。就像一个植物需要适宜的光照、温度和湿度才能茁壮成长一样，我们的身体也需要一个“深度修复”的环境和一系列“助眠”习惯，才能更好地重建睡眠节律，让皮质醇乖乖降下来，褪黑素顺利发挥作用。
这一部分，我们将聚焦于如何从外部环境和日常行为两方面入手，为身体打造一个最佳的睡眠“孵化器”。
4.1 睡前90分钟：关闭“压力开关”的环境准备
当你健身过度，皮质醇飙升导致失眠时，晚上躺在床上可能感觉像是大脑在开派对，各种思绪和焦虑此起彼伏，怎么也平静不下来。这时候，营造一个能够“关闭压力开关”的睡前环境就显得尤为重要。
核心思路是：在睡前90分钟，通过控制光线和温度，为身体创造一个从“清醒模式”逐步过渡到“睡眠模式”的信号，帮助身体自然降低皮质醇，并促进褪黑素的分泌。
1. 光线：调暗灯光，减少蓝光——皮质醇与褪黑素的“光线之战”
光线是调节我们生物钟最强大的外部信号。它就像一个“指挥家”，告诉身体是白天还是黑夜，从而影响皮质醇和褪黑素的分泌。
皮质醇与褪黑素的拮抗关系：简单来说，皮质醇喜欢“亮”，褪黑素喜欢“暗”。早上接触光线，尤其是明亮的光线，能帮助提高皮质醇水平，让我们保持清醒和活力。而到了晚上，光线尤其是蓝光，会强烈抑制褪黑素的分泌 。这就像一个跷跷板，光线一亮，褪黑素就被压下去了；光线一暗，褪黑素才能“浮”起来，开始工作。
具体操作：
- 调暗灯光（<50流明）：在睡前90分钟，尽量将室内灯光调暗，或者只使用亮度较低的夜灯。流明（lumen）是衡量光亮度的单位，50流明大约相当于昏暗的走廊灯或微弱的床头灯。这种昏暗的环境能向身体发出信号：“天黑了，该准备休息了。”
- 减少蓝光暴露：电视、电脑、平板和手机等电子设备发出的蓝光，对褪黑素的抑制作用最强。
- 使用暖光灯泡：将卧室的主灯换成色温较低（通常在2700K以下）的暖光灯泡。这种光线偏黄，对褪黑素的影响较小。
- 手机开启夜间模式/蓝光滤镜：绝大多数智能手机都有“夜间模式”或“护眼模式”，可以减少屏幕发出的蓝光。睡前尤其要开启。
- 远离屏幕：最理想的情况是，睡前90分钟完全避免使用电子屏幕。如果实在需要，可以戴上防蓝光眼镜。
2. 温度：调节室温（18-20℃）——身体降温，更容易入眠
体温的变化也是影响睡眠的关键因素之一。我们入睡时，身体的核心温度会自然下降，并在睡眠过程中保持相对较低的水平。如果卧室温度过高，身体散热困难，就会影响入睡和睡眠质量。
- 体温与睡眠：当环境温度过高时，会影响睡眠质量 71。体温下降是触发睡眠的重要生理机制。
- 具体操作：
- 调节卧室温度至18-20℃：这个温度范围被认为是人体最适宜睡眠的温度。它能帮助身体核心温度缓慢下降，更容易进入睡眠状态。
- 保持卧室通风：睡前可以打开窗户通风几分钟，让新鲜空气进入，并帮助降低室内温度。
- 泡澡/热水淋浴：虽然听起来有点反直觉，但睡前1-2小时洗个热水澡（水温38-40℃），反而能帮助身体更好地降温。洗完澡后，体表血管扩张，热量更容易散发出去，核心体温会随之下降，从而促进睡眠。
通过在睡前90分钟内，有意识地调暗光线、减少蓝光、调节室温，你就是在给身体发出明确的“睡眠信号”，帮助它自然地降低皮质醇，启动褪黑素的分泌，从而更顺利地进入深度修复的睡眠状态。
4.2 放松训练：用“身体扫描”替代“反复复盘”的心理干预
当身体因为过度训练导致皮质醇飙升时，大脑往往会陷入一种“高速运转”的状态。即使身体已经疲惫不堪，思绪却像脱缰的野马，在脑海中“反复复盘”白天的训练、工作，甚至对未来的焦虑也会趁虚而入，让人“躺不平”，难以进入睡眠。这种心理上的紧张和压力，会进一步刺激HPA轴，加剧皮质醇的分泌，形成恶性循环。
这时候，我们需要一些工具来帮助大脑“踩刹车”，从这种持续的应激状态中解脱出来。放松训练就是一种非常有效的心理干预手段。它不仅仅是让你放松身体，更是引导你的思绪从混乱的“反复复盘”中抽离出来，回到当下，关注身体本身。研究表明，包含瑜伽体式的练习有助于改善交感神经系统和下丘脑-垂体-肾上腺系统的调节72，冥想项目可以有效减轻心理压力的负面影响73，正念冥想对抑郁症有积极作用，并且有助于改善焦虑症状74。
这里介绍两种简单易学，且效果显著的放松训练方法：
4.2.1 4-7-8呼吸法：启动身体的“镇静开关”
4-7-8呼吸法，是由哈佛大学医学博士安德鲁·威尔（Andrew Weil）推广的一种简单而强大的呼吸技巧。它被认为可以迅速镇静神经系统，帮助身体从“战或逃”的应激反应中切换到“休息和消化”的放松状态。这项技术因其便捷性，甚至被用于帮助减肥手术后的患者减轻焦虑，改善生活质量 75，并对改善睡眠和缓解疼痛有积极作用 7677。
步骤：
- 准备姿势：找一个舒适的姿势，坐着或躺着都可以。舌尖抵住上颚，就放在门牙后面，并保持在这个位置，直到整个呼吸过程结束。
- 呼气：首先，完全呼出肺部的所有空气，呼气时发出“嘶”的声音。
- 吸气（4秒）：闭上嘴巴，通过鼻子轻轻吸气，同时在心里默数“1、2、3、4”。
- 屏息（7秒）：屏住呼吸，在心里默数“1、2、3、4、5、6、7”。
- 呼气（8秒）：再次呼出肺部的所有空气，呼气时发出“嘶”的声音，在心里默数“1、2、3、4、5、6、7、8”。
- 重复：完成一次呼吸循环（吸气4秒-屏息7秒-呼气8秒），然后再次通过鼻子吸气，重复上述循环。
强调：整个过程要流畅、缓慢，专注地感受呼吸的节奏。如果你一开始屏息7秒或呼气8秒有困难，可以缩短时间，但要保持4:7:8的比例，比如吸气2秒-屏息3.5秒-呼气4秒。重要的是练习，而不是追求完美。
效果：4-7-8呼吸法通过控制呼吸节奏，能够激活副交感神经系统，这是身体的“休息与消化”系统，从而降低心率、血压，减少肌肉紧张，并有助于降低皮质醇水平。多项研究表明，这种呼吸法可以降低焦虑水平 75，并对心率变异性（HRV）和血压有积极影响 78。长期坚持，每日练习2-3次，每次3-4个循环，你会发现它能有效帮助你在睡前平静下来，更快入睡。
4.2.2 渐进式肌肉放松法：从身体到心灵的逐层释放
渐进式肌肉放松法（Progressive Muscle Relaxation, PMR）是一种通过有意识地收紧和放松身体不同部位的肌肉，来感知和缓解身体紧张的技巧。这种方法由Edmund Jacobson在20世纪20年代提出，现在被广泛应用于压力管理和睡眠改善。研究表明，PMR能有效改善绝经期妇女的血管舒缩症状和失眠 79，并能减轻慢性紧张性头痛患者的疼痛和改善睡眠质量 80。对于肺癌患者，PMR也被证实能有效减轻呼吸困难、疼痛并改善睡眠质量 81。
步骤：
- 准备姿势：找一个安静、舒适的地方，躺下或坐下，闭上眼睛。深呼吸几次，感受身体放松。
- 从脚趾到头部：按照以下顺序，逐一收紧并放松身体的各个肌肉群。每个肌肉群先用力收紧（大约5-10秒），感受紧张感，然后突然完全放松（大约15-20秒），感受放松感。在放松时，可以想象紧张感随着呼气离开身体。
- 脚趾：用力卷曲脚趾。放松。
- 脚掌和脚踝：用力绷紧脚掌和脚踝。放松。
- 小腿：用力收紧小腿肌肉（如绷脚尖）。放松。
- 大腿：收紧大腿前侧和后侧肌肉。放松。
- 臀部：收紧臀部肌肉。放松。
- 腹部：收紧腹部肌肉，像要把肚脐吸向脊椎一样。放松。
- 胸部：深吸一口气，收紧胸部肌肉。放松，慢慢呼气。
- 背部：拱起背部，收紧背部肌肉。放松。
- 双手：握紧拳头。放松。
- 手臂：弯曲肘部，收紧二头肌。放松。
- 肩膀：耸起肩膀，靠近耳朵。放松，让肩膀下沉。
- 颈部：轻轻向后仰头，感受颈部后侧紧张。放松。
- 面部：紧皱眉头、闭紧眼睛、紧咬牙关。放松，感受面部肌肉舒展。
强调：在整个过程中，专注于感受紧张和放松的对比。当你放松时，注意身体的温暖、沉重和舒展感。如果某个部位特别紧张，可以在该部位重复几次。
效果：PMR通过让身体经历紧张到放松的过程，教会大脑和身体如何识别并释放肌肉紧张。它不仅能帮助你缓解身体上的疲劳和酸痛，还能打断大脑中“反复复盘”的思绪，将注意力引导回身体，从而减少心理压力和焦虑，为入睡创造有利条件。研究表明，PMR与其他放松疗法（如认知行为疗法）结合使用，对慢性疼痛和睡眠质量有显著改善作用 82。睡前进行10-15分钟的渐进式肌肉放松，你会发现身体会变得异常轻松，更容易进入深度睡眠。
长期效果：无论是4-7-8呼吸法还是渐进式肌肉放松法，其效果都并非立竿见影，贵在每日10分钟的长期坚持。它们就像是给大脑和身体进行“放松训练”，随着时间的推移，你的身体会更容易进入放松状态，从而更有效地对抗皮质醇的飙升，重建健康的睡眠节律。
4.3 白天光照：用“自然闹钟”强化昼夜节律
如果说夜晚的光线是影响褪黑素分泌的“杀手”，那么白天的光线，尤其是晨间光照，就是我们身体里调节皮质醇和褪黑素节律的“自然闹钟”。它能够有效地强化我们的昼夜节律，让身体知道什么时候该清醒，什么时候该休息，从而帮助皮质醇在夜间乖乖地降下来，为优质睡眠做好准备。
我们的身体内部有一个精密的生物钟，它控制着包括皮质醇和褪黑素分泌在内的许多生理节律。这个生物钟对光线极其敏感，尤其是早晨的光线。当早晨明亮的光线（特别是富含蓝光成分的白光）照射到我们的眼睛时，视网膜中的特殊细胞会接收到这个信号，并将其传递给大脑中的生物钟中心（下丘脑的视交叉上核）。生物钟中心就会根据这个信号，调整身体的各种节律，包括告诉HPA轴在白天分泌皮质醇，让身体保持清醒和活力，同时抑制夜间褪黑素的分泌，为白天的活动做好准备；而在夜晚，随着光线减弱，生物钟会促进褪黑素的分泌，帮助我们入睡 。
晨间光照与皮质醇觉醒反应（CAR）
晨间光照对皮质醇的影响尤其体现在皮质醇觉醒反应（Cortisol Awakening Response, CAR）上。CAR指的是我们在醒来后的30-45分钟内，皮质醇水平会迅速升高，达到一个峰值，这个生理现象被认为是身体准备应对即将到来的白天压力的表现，也是良好昼夜节律健康的标志之一。研究表明，早晨接触光照，尤其是明亮的光照，可以有效调节这个皮质醇觉醒反应，帮助身体更好地启动一天的生理活动 8384。这意味着，一个健康的CAR有助于在白天保持清醒和专注，避免过度依赖高皮质醇来维持警觉。
反之，如果我们长期缺乏白天的自然光照，比如长时间待在室内、办公室光线不足，或者过度依赖人造光源，我们的生物钟就会变得混乱。它会“搞不清楚”现在是白天还是黑夜，导致皮质醇的昼夜节律失调——白天不够高，晚上又降不下来，从而加剧失眠问题 858687。同时，夜晚光线，尤其是蓝光暴露，会抑制褪黑素分泌，进一步干扰睡眠 88。
如何利用“自然闹钟”强化昼夜节律？
为了对抗皮质醇飙升导致的失眠，并重建健康的睡眠节律，我们需要有意识地利用晨间光照来“校准”我们的生物钟：
- 晨起后30分钟内，接受10000勒克斯的自然光：
- 走到户外：这是最直接、最有效的方式。每天早上醒来后，即使只是10-30分钟，到户外去晒晒太阳，感受自然光线。不需要直射阳光，即使是阴天，户外的光照强度也远高于室内。例如，在公园散步，或者在阳台上喝杯水，都能帮助你的身体接收到足够的光线信号。
- 窗边活动：如果无法出门，坐在窗边，拉开窗帘，让阳光照进来，也能起到一定的作用。尽量选择朝东的窗户，能最早接收到日出光线。
- 光照治疗设备（Light Therapy Lamp）：对于那些居住在光照不足的地区，或者因工作等原因无法接触自然光的人群，可以考虑使用光照治疗设备。例如，一项针对失眠症患者的研究中，使用特定光照设备（6000 K, 380 lux）进行光照治疗被证明可以改善白天嗜睡情况，虽然其亮度和光谱与自然光有差异，但仍可在一定程度上辅助调节生物钟 89。
光照治疗设备的选择与注意事项：
- 亮度：确保选择亮度达到10000勒克斯的设备。
- 光谱：优先选择全光谱或模拟自然光光谱的设备。
- 使用距离：根据产品说明，确保在有效距离内使用，以便光线能够充分进入眼睛。
- 避免直视：虽然光照治疗设备是安全的，但仍应避免长时间直视光源。
- 时间：最好在早晨起床后尽快使用，而不是在下午或晚上，以免干扰夜间睡眠。
通过积极利用晨间光照，我们能够有效地向身体发出“日出”的信号，帮助重置和强化昼夜节律。这将有助于在白天维持较高的警觉性和能量，并在夜晚促进褪黑素的正常分泌，让皮质醇在正确的时间下降，最终帮助我们摆脱失眠困扰，实现深度修复的睡眠。
5. 应急处理：皮质醇飙升当晚的3个快速助眠技巧
5.1 局部降温法：用“物理冷静”打断应激状态
当皮质醇飙升让你在床上辗转反侧，怎么也睡不着的时候，你需要一些快速有效的“物理冷静”方法来帮助身体打破这种应激状态，尽快进入睡眠模式。其中一个非常有效且被科学验证的方法就是——局部降温。
你可能听过“睡觉要凉着睡”的说法，这背后有科学依据。我们的身体在入睡前，核心体温会自然下降。这种体温的下降是启动睡眠的重要生理机制 9091。睡眠相关的核心体温下降是通过减少新陈代谢产热，以及改变自主神经系统活动和体温调节效应器活动来实现的，其中交感神经对周围血管的张力降低，导致通过皮肤散热，表现为与睡眠开始相关的远端皮肤温度升高 90。
如果皮质醇高企，身体处于应激状态，体温调节可能会受到影响，导致核心体温降不下来，让你感到“燥热”而难以入睡。这时，我们可以通过一些巧妙的局部降温方法，来“骗过”身体，促使它启动体温下降的机制，从而加速入睡。
具体操作：
冷毛巾敷手腕/脚踝1-2分钟：
- 原理：手腕和脚踝是身体散热较快的部位，因为这些地方的血管相对靠近皮肤表面。通过局部敷冷毛巾，可以迅速降低这些部位的皮肤温度，促使全身血管扩张，加速血液循环，从而更有效地将身体内部的热量散发出去，帮助核心体温下降。
- 操作：准备一条湿润的冷毛巾（可以在冰箱里稍微冷藏一下，或用冷水浸湿拧干），在睡前或感到难以入睡时，将其敷在手腕内侧或脚踝处，持续1-2分钟，直到感觉这些部位凉爽舒适。
睡前泡脚后擦干（通过蒸发散热降低核心体温）：
小贴士：
- 局部冷却设备：市面上也有一些专门用于局部冷却的设备，例如腕带式的冷却设备，可以在需要时提供局部冷刺激。一项研究表明，腕带式局部冷却干预可以降低远端皮肤温度，但对主观睡眠质量没有显著影响 96。而另一项针对慢性失眠患者的研究则显示，使用前额冷却装置（14-16℃）能够改善入睡潜伏期、夜间觉醒时间，并显著缓解失眠、焦虑和抑郁症状 9798。这提示局部冷却对于某些人群可能有益。
- 温度适宜：降温不是越冰越好，要以自身感觉舒适为宜。过度冰冷反而可能引起身体的应激反应。
- 结合其他助眠方法：局部降温法可以作为你睡前准备的一部分，结合之前提到的调暗灯光、放松训练等，效果会更好。
通过这些简单的“物理冷静”技巧，你可以主动干预身体的温度调节，帮助身体从“应激模式”切换到“准备睡眠模式”，从而更有效地对抗皮质醇飙升带来的失眠困扰。
5.2 认知转移术：从“焦虑明天”到“专注当下”的思维切换
当你因为健身过度导致皮质醇飙升而失眠时，最常见的场景就是：身体虽然疲惫不堪地躺在床上，但大脑却像一台永不停歇的机器，不断地播放着各种“焦虑大片”——今天的训练是不是过量了？明天的表现会不会下滑？工作上的事情还没搞定怎么办？甚至会“复盘”一些鸡毛蒜皮的小事。这种“越想睡越清醒”的状况，正是皮质醇升高带来的典型心理反应，它让你的大脑持续处于兴奋和警觉状态，形成一个难以打破的恶性循环。
在这样的时刻，如果一味地强迫自己“不要想”，反而会适得其反。因为大脑就像一个弹簧，你越是压制它，它反弹得越厉害。我们需要的是一种巧妙的“认知转移”技巧，将大脑的注意力从那些令人焦虑的思绪中，温柔而坚定地拉回到当下，关注你所处的环境和身体的感受。这种方法能帮助你打断负面思维的循环，让大脑从“未来焦虑模式”切换到“当下平静模式”，从而为睡眠创造条件。
这里介绍一种简单易学、效果显著的认知转移技巧——“5-4-3-2-1感官着陆法”。它源于正念疗法，旨在帮助你快速将注意力集中于当前时刻，通过调动五种感官来“锚定”现实，从而驱散脑海中的杂念。
“5-4-3-2-1感官着陆法”步骤：
当你感到焦虑或无法入睡时，请尝试以下步骤，并尽量保持缓慢而深长的呼吸：
说出5个你“看”到的物体：环顾你的房间（即使在黑暗中，你也能看到一些模糊的轮廓），或者闭上眼睛，在脑海中浮现出5个你此刻能看到的东西。比如：床头的台灯、衣柜的边缘、窗外的夜色、天花板的纹理、墙上的画。不必纠结于细节，只需识别出它们的存在。
说出4种你“触摸”到的触感：将注意力放在你的身体上，感受4种你能触摸到的触感。比如：身体与床垫的接触、被子盖在皮肤上的轻柔感、睡衣的材质、枕头对头部的支撑。你可以轻轻触摸床单、自己的手臂，感受它们的质地和温度。
说出3种你“听”到的声音：倾听周围的环境，识别出3种你此刻能听到的声音。比如：窗外微弱的风声、远处汽车的驶过声、自己的呼吸声、时钟滴答的声音（如果有时钟）。不必刻意寻找，只需留意那些自然进入耳中的声音。
说出2种你“闻”到的气味：将注意力转移到嗅觉。试着分辨出2种你能闻到的气味。比如：空气中淡淡的清洁剂味道、卧室特有的气味、枕头上的清香。如果闻不到两种，一种也可以。
说出1种你“尝”到的味道：最后，专注于你的味觉。也许是睡前牙膏的余味、口中淡淡的唾液味道，或者是你今天吃过的食物留在口中的一丝味道。
这项技巧为何有效？
“5-4-3-2-1感官着陆法”的强大之处在于：
- 强制注意力转移：它迫使你的大脑从抽象的、未来的、负面的思绪中抽离，转而专注于具体的、当下的感官信息。大脑一次只能处理有限的信息，当你专注于感官时，那些令人焦虑的思绪就会暂时被“挤”出去。
- 激活不同脑区：通过调动视觉、触觉、听觉、嗅觉和味觉，可以激活大脑的不同区域，从而打断惯常的思维路径，帮助大脑“重启”。
- 培养正念：这个过程本身就是一种简单的正念练习，让你学会活在当下，而不是被过去或未来的担忧所困扰。研究表明，正念练习能有效降低压力、改善睡眠质量。99100101102长期冥想可能与改善睡眠质量有关103。虽然正念减压（MBSR）能够改善心理健康和感知压力，但直接影响皮质醇水平的证据尚不明确，有研究未观察到皮质醇水平的变化104。
当你因为皮质醇飙升而无法入睡时，请不要纠结于“为什么睡不着”，也不要强迫自己“必须睡着”。而是尝试用“5-4-3-2-1感官着陆法”来温柔地引导你的大脑，从“焦虑明天”切换到“专注当下”。你会发现，当你的注意力回到现实，身心逐渐平静下来时，睡眠自然会悄然而至。
5.3 短期辅助：安全使用“天然助眠剂”的注意事项
当你因为过度训练导致皮质醇飙升，失眠成了家常便饭时，可能会忍不住想寻求一些“外援”来帮助自己快速入睡。市面上充斥着各种助眠产品，但并非所有都安全有效。在使用任何助眠剂之前，务必了解其作用机制和潜在风险。我们的目标是安全地度过急性失眠期，而不是养成对药物的依赖。
1. 优先选择食物补充，特别是镁元素
我们前面在“3.1 镁元素：天然的‘压力缓冲剂’如何改善睡眠”中详细介绍过，镁对于缓解压力、降低皮质醇、促进褪黑素分泌以及改善睡眠质量都有着重要的作用。
证据支持：多项研究表明，镁补充剂对改善失眠症状有效，尤其是在老年人中，可以缩短入睡时间、提高睡眠效率、减少早醒，并降低皮质醇水平 232528。例如，一项针对糖尿病患者的研究发现，镁补充剂能够显著降低皮质醇水平，提高褪黑素水平，并改善失眠的严重程度和睡眠时长 23。另一项针对老年人的双盲、安慰剂对照临床试验也证实，镁补充剂能改善主观和客观的睡眠指标，包括降低皮质醇浓度 25。
建议：在考虑任何补充剂之前，请务必优先通过饮食来补充镁。富含镁的食物包括深绿色蔬菜（如菠菜）、坚果（如南瓜籽、杏仁）、全谷物、豆类和黑巧克力。如果你的饮食中镁摄入不足，或者在皮质醇飙升导致失眠的急性期，可以考虑在医生或营养师指导下，短期补充镁制剂。推荐剂量通常为每日400-500mg，可以在睡前2小时服用，效果可能更佳。
2. 避免苯二氮䓬类药物：小心“假睡”和成瘾风险
当焦虑和失眠达到顶点时，一些人可能会寻求苯二氮䓬类药物（如地西泮、劳拉西泮等）的帮助。这类药物通过增强大脑中伽马氨基丁酸（GABA）的作用来镇静神经，确实能快速诱导睡眠。
风险：
建议：除非在医生明确诊断并严格指导下短期使用，否则健身人群应尽量避免使用苯二氮䓬类药物来应对失眠。它们带来的短期缓解无法解决根本问题，反而会带来更大的长期风险。
3. 褪黑素：谨慎使用，剂量和时长有讲究
褪黑素是人体自然分泌的一种激素，主要负责调节我们的睡眠-觉醒周期。当皮质醇飙升抑制了褪黑素的分泌时，补充褪黑素似乎是一个直接的解决方案。
机制与证据：褪黑素在体内扮演着“睡眠信号员”的角色，它向大脑发出信号：“天黑了，该睡觉了”。适量补充褪黑素可以帮助调整生物钟，缩短入睡时间，改善睡眠质量，尤其对于那些生物钟紊乱（如倒时差、轮班工作）或自身褪黑素分泌不足的人群 108109。一项研究发现，褪黑素补充剂可以显著提高糖尿病患者的褪黑素水平，并改善失眠严重程度 23。
建议：
- 咨询医生：在使用褪黑素之前，最好先咨询医生，以确定是否适合你，并获取正确的指导。
- 剂量控制：褪黑素并非越多越好。通常建议从低剂量开始（如0.5mg-1mg），一般不超过3mg。过高剂量的褪黑素反而可能导致次日嗜睡、头痛等副作用，并且可能扰乱身体自然的褪黑素分泌。
- 短期使用：褪黑素主要用于短期调整睡眠节律，例如倒时差或短期失眠。不建议连续使用超过2周。长期使用褪黑素的潜在风险和效果仍需更多研究证实 108。
- 服用时间：通常建议在睡前30-60分钟服用，让身体有时间吸收并发挥作用。
- 非万能药：褪黑素并不能解决所有类型的失眠问题。如果失眠是由于严重的心理压力、焦虑或抑郁引起，褪黑素的效果可能有限。
请记住，这些“天然助眠剂”只是短期辅助手段。应对皮质醇飙升导致的失眠，最根本的解决方案仍然是：合理调整训练、优化饮食、重建健康的睡眠环境和习惯，并学会管理压力。药物和补充剂只是工具，不能替代健康的生活方式。
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参考文献
1Hormonal responses and adaptations to resistance exercise and training.PubMed
William J Kraemer, Nicholas A Ratamess
Sports Med. 2005;35(4):339-61. doi: 10.2165/00007256-200535040-00004.
Resistance exercise has been shown to elicit a significant acute hormonal response. It appears that this acute response is more critical to tissue growth and remodelling than chronic changes in resting hormonal concentrations, as many studies have not shown a significant change during resistance training despite increases in muscle strength and hypertrophy. Anabolic hormones such as testosterone and the superfamily of growth hormones (GH) have been shown to be elevated during 15-30 minutes of post-resistance exercise providing an adequate stimulus is present. Protocols high in volume, moderate to high in intensity, using short rest intervals and stressing a large muscle mass, tend to produce the greatest acute hormonal elevations (e.g. testosterone, GH and the catabolic hormone cortisol) compared with low-volume, high-intensity protocols using long rest intervals. Other anabolic hormones such as insulin and insulin-like growth factor-1 (IGF-1) are critical to skeletal muscle growth. Insulin is regulated by blood glucose and amino acid levels. However, circulating IGF-1 elevations have been reported following resistance exercise presumably in response to GH-stimulated hepatic secretion. Recent evidence indicates that muscle isoforms of IGF-1 may play a substantial role in tissue remodelling via up-regulation by mechanical signalling (i.e. increased gene expression resulting from stretch and tension to the muscle cytoskeleton leading to greater protein synthesis rates). Acute elevations in catecholamines are critical to optimal force production and energy liberation during resistance exercise. More recent research has shown the importance of acute hormonal elevations and mechanical stimuli for subsequent up- and down-regulation of cytoplasmic steroid receptors needed to mediate the hormonal effects. Other factors such as nutrition, overtraining, detraining and circadian patterns of hormone secretion are critical to examining the hormonal responses and adaptations to resistance training.
2Hypothalamic-Pituitary-Adrenal (HPA) Axis Functioning in Overtraining Syndrome: Findings from Endocrine and Metabolic Responses on Overtraining Syndrome (EROS)-EROS-HPA Axis.PubMed
Flavio A Cadegiani, Claudio E Kater
Sports Med Open. 2017 Dec 8;3(1):45. doi: 10.1186/s40798-017-0113-0.
BACKGROUND: Overtraining syndrome (OTS) results from excessive training load without adequate recovery and leads to decreased performance and fatigue. The pathophysiology of OTS in athletes is not fully understood, which makes accurate diagnosis difficult. Previous studies indicate that alterations in the hypothalamus-pituitary-adrenal (HPA) axis may be responsible for OTS; however, the data is not conclusive. This study aimed to compare, through gold standard and exercise-independent tests, the response of the HPA axis in OTS-affected athletes (OTS group) to healthy physically active subjects (ATL group) and healthy non-active subjects (NCS group). METHODS: Selected subjects were evaluated for cortisol response to a 250-μg cosyntropin stimulation test (CST), cortisol and adrenocorticotropic hormone (ACTH) responses during an insulin tolerance test (ITT), and salivary cortisol rhythm (SCR). RESULTS: A total of 51 subjects were included (OTS, n = 14; ATL, n = 25; and NCS, n = 12). Cortisol response in the CST was similar among the three groups. Conversely, mean cortisol response during an ITT was significantly higher in ATL (21.7 μg/dL; increase = 9.2 μg/dL) compared to OTS (17.9 μg/dL; 6.3 μg/dL) and NCS (16.9 μg/dL; 6.0 μg/dL) (p ≤ 0.001; p = 0.01). Likewise, median ACTH response during an ITT was significantly higher in ATL (91.4 pg/mL; increase = 45.1 pg/mL) compared to OTS (30.3 pg/mL; 9.7 pg/mL) and NCS (51.4 pg/mL; 38.0 pg/mL) (p = 0.006; p = 0.004). For SCR, mean cortisol 30 min after awakening was significantly higher in ATL (500 ng/dL) compared to OTS (323 ng/dL) and NCS (393 ng/dL) (p = 0.004). We identified the following cutoffs that could help exclude or confirm OTS: cortisol level at 30 min after awakening (exclusion = > 530 ng/dL); cortisol response to ITT (exclusion = > 20.5 μg/dL; confirmation = < 17 μg/dL or increase < 9.5 μg/dL); and ACTH response (exclusion = > 106 pg/mL or increase > 70 pg/mL; confirmation = < 35 pg/mL and increase < 14.5 pg/mL). CONCLUSION: The findings of the present study showed that healthy athletes disclose adaptions to exercises that helped improve sport-specific performance, whereas this sort of hormonal conditioning was at least partially lost in OTS, which may explain the decrease in performance in OTS.
3Molecular links between endocrine, nervous and immune system during chronic stress.PubMed
Roberto Zefferino, Sante Di Gioia, Massimo Conese
Brain Behav. 2021 Feb;11(2):e01960. doi: 10.1002/brb3.1960. Epub 2020 Dec 8.
INTRODUCTION: The stress response is different in various individuals, however, the mechanisms that could explain these distinct effects are not well known and the molecular correlates have been considered one at the time. Particular harmful conditions occur if the subject, instead to cope the stressful events, succumb to them, in this case, a cascade reaction happens that through different signaling causes a specific reaction named "sickness behaviour." The aim of this article is to review the complex relations among important molecules belonging to Central nervous system (CNS), immune system (IS), and endocrine system (ES) during the chronic stress response. METHODS: After having verified the state of art concerning the function of cortisol, norepinephrine (NE), interleukin (IL)-1β and melatonin, we describe as they work together. RESULTS: We propose a speculative hypothesis concerning the complex interplay of these signaling molecules during chronic stress, highlighting the role of IL-1β as main biomarker of this effects, indeed, during chronic stress its increment transforms this inflammatory signal into a nervous signal (NE), in turn, this uses the ES (melatonin and cortisol) to counterbalance again IL-1β. During cortisol resistance, a vicious loop occurs that increments all mediators, unbalancing IS, ES, and CNS networks. This IL-1β increase would occur above all when the individual succumbs to stressful events, showing the Sickness Behaviour Symptoms. IL-1β might, through melatonin and vice versa, determine sleep disorders too. CONCLUSION: The molecular links here outlined could explain how stress plays a role in etiopathogenesis of several diseases through this complex interplay.
4Mechanisms underlying the association between insomnia, anxiety, and depression in adolescence: Implications for behavioral sleep interventions.PubMed
Matthew J Blake, John A Trinder, Nicholas B Allen
Clin Psychol Rev. 2018 Jul;63:25-40. doi: 10.1016/j.cpr.2018.05.006. Epub 2018 May 28.
There is robust evidence of an association between insomnia, anxiety, and depression in adolescence. The aim of this review is to describe and synthesize potential mechanisms underlying this association and explore implications for the design of adolescent behavioral sleep interventions. Specifically, we examine whether insomnia symptoms are a mechanism for the development of internalizing symptoms in adolescence and whether sleep interventions are an effective treatment for both insomnia and internalizing symptoms in adolescence because they target the shared mechanisms underlying these disorders. Research using different methodologies points to the role of sequential, parallel, and interacting mechanisms. In this paper, we review a wide range of relevant biological (i.e., polymorphisms and dysregulation in serotonin, dopamine, and circadian clock genes; alterations in corticolimbic and mesolimbic brain circuits; cortisol reactivity to stress; inflammatory cytokine dysregulation; biased memory consolidation; changes in sleep architecture), psychological (i.e., cognitive inflexibility, interpretational biases, judgment biases, negative attribution styles, worry, rumination, biased attention to threat, dysfunctional beliefs and attitudes about sleep, misperception of sleep deficit), and social mechanisms (i.e., reduced and impaired social interactions, unhelpful parenting behaviors, family stress) and propose an integrative multilevel model of how these phenomena may interact to increase vulnerability to both insomnia and internalizing disorders. Several 'biopsychosocial' mechanisms hold promise as viable treatment targets for adolescent behavioral sleep interventions, which may reduce both insomnia and internalizing symptoms.
5The Effects of Insomnia and Sleep Loss on Cardiovascular Disease.PubMed
Meena S Khan, Rita Aouad
Sleep Med Clin. 2022 Jun;17(2):193-203. doi: 10.1016/j.jsmc.2022.02.008.
Sleep loss has negative impacts on quality of life, mood, cognitive function and heath. Insomnia or difficulty sleeping is also a prevalent issue, affecting up to 35% of the population at some point in their lives. Insomnia is linked to poor mood, increased use of health care resources, and decreased quality of life as well as possible links to cardiovascular risk factors and disease. Studies have shown an increase in cortisol levels, decreased immunity, and increased markers of sympathetic activity in sleep-deprived healthy subjects and those with chronic insomnia. The literature also shows that subjective complaints consistent with chronic insomnia and shortened sleep time, both independently and in combination, can be associated with the development of diabetes, hypertension, and cardiovascular disease. In this article, we will explore the relationship and strength of association between insufficient sleep and insomnia with these health conditions.
6The effect of acute sleep deprivation on skeletal muscle protein synthesis and the hormonal environment.PubMed
Séverine Lamon, Aimee Morabito, Emily Arentson-Lantz, et al.
Physiol Rep. 2021 Jan;9(1):e14660. doi: 10.14814/phy2.14660.
Chronic sleep loss is a potent catabolic stressor, increasing the risk of metabolic dysfunction and loss of muscle mass and function. To provide mechanistic insight into these clinical outcomes, we sought to determine if acute sleep deprivation blunts skeletal muscle protein synthesis and promotes a catabolic environment. Healthy young adults (N = 13; seven male, six female) were subjected to one night of total sleep deprivation (DEP) and normal sleep (CON) in a randomized cross-over design. Anabolic and catabolic hormonal profiles were assessed across the following day. Postprandial muscle protein fractional synthesis rate (FSR) was assessed between 13:00 and 15:00 and gene markers of muscle protein degradation were assessed at 13:00. Acute sleep deprivation reduced muscle protein synthesis by 18% (CON: 0.072 ± 0.015% vs. DEP: 0.059 ± 0.014%·h , p = .040). In addition, sleep deprivation increased plasma cortisol by 21% (p = .030) and decreased plasma testosterone by 24% (p = .029). No difference was found in the markers of protein degradation. A single night of total sleep deprivation is sufficient to induce anabolic resistance and a procatabolic environment. These acute changes may represent mechanistic precursors driving the metabolic dysfunction and body composition changes associated with chronic sleep deprivation.
7Exercise and circulating cortisol levels: the intensity threshold effect.PubMed
E E Hill, E Zack, C Battaglini, et al.
J Endocrinol Invest. 2008 Jul;31(7):587-91. doi: 10.1007/BF03345606.
This study examined the influence of exercise intensity upon the cortisol response of the hypothalamic-pituitary-adrenal (HPA) axis. Specifically, we examined exercise at intensities of 40, 60, and 80% maximal oxygen uptake (VO2max) in an attempt to determine the intensity necessary to provoke an increase in circulating cortisol. Twelve active moderately trained men performed 30 min of exercise at intensities of 40, 60, and 80% of their VO2max, as well as a 30-min resting-control session involving no exercise on separate days. Confounding factors such as time of day--circadian rhythms, prior diet--activity patterns, psychological stress, and levels of exercise training were controlled. Cortisol and ACTH were assessed in blood collected immediately before (pre-) and after (post-) each experimental session. Statistical analysis involved repeated measures analysis of variance and Tukey post-hoc testing. The percent change in cortisol from pre- to post-sampling at each session was: resting-control, 40, 60, and 80% sessions (mean+/-SD) =-6.6+/-3.5%, +5.7+/-11.0%, +39.9+/-11.8%, and +83.1+/-18.5%, respectively. The 60% and 80% intensity magnitude of change was significantly greater than in the other sessions, as well as from one to another. The ACTH responses mirrored those of cortisol, but only the 80% exercise provoked a significant (p<0.05) increase pre- to post-exercise. The calculated changes in plasma volume for the resting-control, 40%, 60%, and 80% sessions were: +2.2+/-3.0%, -9.9+/-5.0%, -15.6+/-3.5%, and -17.2+/-3.3%, respectively. Collectively, the cortisol findings support the view that moderate to high intensity exercise provokes increases in circulating cortisol levels. These increases seem due to a combination of hemoconcentration and HPA axis stimulus (ACTH). In contrast, low intensity exercise (40%) does not result in significant increases in cortisol levels, but, once corrections for plasma volume reduction occurred and circadian factors were examined, low intensity exercise actually resulted in a reduction in circulating cortisol levels.
8Hypothalamic dysfunction in overtrained athletes.PubMed
J L Barron, T D Noakes, W Levy, et al.
J Clin Endocrinol Metab. 1985 Apr;60(4):803-6. doi: 10.1210/jcem-60-4-803.
Some athletes who undertake strenuous training programs for a prolonged period of time develop the overtraining syndrome. The pathophysiology of the condition is unknown. Hypothalamic-pituitary function was studied by determining the hormonal responses to insulin-induced hypoglycemia in five asymptomatic male marathon runners during a 4-month period in which they ran 42-, 56-, and 92-km races and in four overtrained male athletes. The response of the asymptomatic runners was not different when tested 1 month before and within 48 h after the 42- and 92-km races. All four overtrained athletes presented with impaired training and racing times, apathy, and a heavy-legged feeling and were tested when overtrained and again after 4 weeks of rest. The plasma cortisol, ACTH, GH, and PRL responses to insulin-induced hypoglycemia in the four overtrained athletes were lower than their responses after the rest and lower than the responses of the asymptomatic runners. In both groups, the LH, TSH, and PRL responses to LHRH and TRH were normal. The impaired hormonal responses to insulin-induced hypoglycemia, with recovery after 4 weeks of rest, indicate hypothalamic dysfunction and may be a diagnostic marker of the overtraining syndrome.
9Hormonal balance and nutritional intake in elite tactical athletes.PubMed
Andrew E Jensen, Laura J Arrington, Lorraine P Turcotte, et al.
Steroids. 2019 Dec;152:108504. doi: 10.1016/j.steroids.2019.108504. Epub 2019 Oct 3.
Chronic exposure to multifactorial stress, such as that endured by elite military operators, may lead to overtraining syndrome and negatively impact hormonal regulation. In acute settings (<6 mos), military training has been shown to lead to hormonal dysfunction; however, less is known about the consequences of long-term military training. Thus, the purpose of this study was to determine the chronic effects of military operations and training on the hormone profile of elite military operators. A cross-sectional, random sample of active duty elite US military operators (n = 65, age = 29.8 ± 1.0 yrs, height = 178.4 ± 0.7 cm, weight = 85.1 ± 2.0 kg) concomitantly engaged in rigorous physical training were recruited to participate in the study. Following an overnight fast, waking plasma concentrations of luteinizing hormone, total testosterone (TT), free testosterone, sex-hormone binding globulin, cortisol, thyroid stimulating hormone, triiodothyronine, and thyroxine were obtained. Data were analyzed for correlations and compared against normative reference values. There was a significant positive correlation between TT and cortisol (R = 0.07; P = 0.038). In addition, 43% of the participants (n = 28) had TT below age-based normative reference ranges. These results indicate that long-term military operations and training may place a large burden on the operators and depress or alter the hypothalamic pituitary, adrenal, gonadal, and thyroid axes.
10Basal Hormones and Biochemical Markers as Predictors of Overtraining Syndrome in Male Athletes: The EROS-BASAL Study.PubMed
Flavio A Cadegiani, Claudio E Kater
J Athl Train. 2019 Aug;54(8):906-914. doi: 10.4085/1062-6050-148-18. Epub 2019 Aug 6.
CONTEXT: Overtraining syndrome (OTS) and related conditions cause decreased training performance and fatigue through an imbalance among training volume, nutrition, and recovery time. No definitive biochemical markers of OTS currently exist. OBJECTIVE: To compare muscular, hormonal, and inflammatory parameters among OTS-affected athletes, healthy athletes, and sedentary controls. DESIGN: Cross-sectional study. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: Fifty-one men aged 18 to 50 years (14 OTS-affected athletes [OTS group], 25 healthy athletes [ATL group], and 12 healthy sedentary participants [NCS group]), with a body mass index of 20 to 30.0 kg/m (sedentary) or 20 to 33.0 kg/m (athletes), recruited through social media. All 39 athletes performed both endurance and resistance sports. MAIN OUTCOME MEASURE(S): We measured total testosterone, estradiol, insulin-like growth factor 1, thyroid-stimulating hormone, free thyronine, total and fractioned catecholamines and metanephrines, lactate, ferritin, creatinine, creatine kinase, erythrocyte sedimentation rate, C-reactive protein, lipid profile, hemogram, and testosterone : estradiol, testosterone : cortisol, neutrophil : lymphocyte, platelet: lymphocyte, and catecholamine : metanephrine ratios. Each parameter was statistically analyzed through 3-group comparisons, and whenever < .05, pairwise comparisons were performed (OTS × ATL, OTS × NCS, and ATL × NCS). RESULTS: Neutrophils and testosterone were lower in the OTS group than in the ATL group but similar between the OTS and NCS groups. Creatine kinase, lactate, estradiol, total catecholamines, and dopamine were higher in the OTS group than in the ATL and NCS groups, whereas the testosterone : estradiol ratio was lower, even after adjusting for all variables. Lymphocytes were lower in the ATL group than in the OTS and NCS groups. The ATL and OTS groups trained with the same intensity, frequency, and types of exercise. CONCLUSIONS: At least in males, OTS was typified by increased estradiol, decreased testosterone, overreaction of muscle tissue to physical exertion, and immune system changes, with deconditioning effects of the adaptive changes observed in healthy athletes.
11Sleep deprivation and stress: a reciprocal relationship.PubMed
Mathieu Nollet, William Wisden, Nicholas P Franks
Interface Focus. 2020 Jun 6;10(3):20190092. doi: 10.1098/rsfs.2019.0092. Epub 2020 Apr 17.
Sleep is highly conserved across evolution, suggesting vital biological functions that are yet to be fully understood. Animals and humans experiencing partial sleep restriction usually exhibit detrimental physiological responses, while total and prolonged sleep loss could lead to death. The perturbation of sleep homeostasis is usually accompanied by an increase in hypothalamic-pituitary-adrenal (HPA) axis activity, leading to a rise in circulating levels of stress hormones (e.g. cortisol in humans, corticosterone in rodents). Such hormones follow a circadian release pattern under undisturbed conditions and participate in the regulation of sleep. The investigation of the consequences of sleep deprivation, from molecular changes to behavioural alterations, has been used to study the fundamental functions of sleep. However, the reciprocal relationship between sleep and the activity of the HPA axis is problematic when investigating sleep using traditional sleep-deprivation protocols that can induce stress . This is especially true in studies using rodents in which sleep deprivation is achieved by exogenous, and potentially stressful, sensory-motor stimulations that can undoubtedly confuse their conclusions. While more research is needed to explore the mechanisms underlying sleep loss and health, avoiding stress as a confounding factor in sleep-deprivation studies is therefore crucial. This review examines the evidence of the intricate links between sleep and stress in the context of experimental sleep deprivation, and proposes a more sophisticated research framework for sleep-deprivation procedures that could benefit from recent progress in biotechnological tools for precise neuromodulation, such as chemogenetics and optogenetics, as well as improved automated real-time sleep-scoring algorithms.
12Effects of Overtraining Status on the Cortisol Awakening Response-Endocrine and Metabolic Responses on Overtraining Syndrome (EROS-CAR).PubMed
Travis Anderson, Laurie Wideman, Flavio A Cadegiani, et al.
Int J Sports Physiol Perform. 2021 Jul 1;16(7):965-973. doi: 10.1123/ijspp.2020-0205. Epub 2021 Mar 3.
UNLABELLED: The cortisol awakening response (CAR) is a distinct component of the circadian cortisol profile and has promise as a biomarker for the monitoring of athlete readiness and training status. Although some studies have suggested the CAR may be affected by the development of overtraining syndrome (OTS), this has yet to be systematically investigated. PURPOSE: To compare the CAR and diurnal cortisol slope between athletes diagnosed with OTS, healthy athletes, and sedentary controls. METHODS: This study was a secondary analysis of data from the Endocrine and Metabolic Responses on Overtraining study. Male participants were recruited to either OTS, healthy athlete, or sedentary control groups. The participants produced saliva samples immediately after waking (S1), 30 minutes after waking (S2), at 16:00 hours, and at 23:00 hours. Salivary cortisol concentration was determined by an electrochemiluminescence assay. Mixed-effects models were used to assess the conditional effect of group (sedentary controls, OTS, and healthy athletes) on the change in cortisol over time. Separate models were fit for the awakening samples (S1 and S2) and for the diurnal slope (linear change across S1, 16:00 h, and 23:00 h). RESULTS: The models demonstrated significant time-by-group interaction for OTS for the 2 cortisol concentrations collected during the awakening period (β = -9.33, P < .001), but not for the diurnal cortisol slope (β = 0.02, P = .80). CONCLUSIONS: These results suggest the CAR may be associated with OTS and should be considered within a panel of biomarkers. Further research is necessary to determine whether alterations in the CAR may precede the diagnosis of OTS.
13Overtraining syndrome: a practical guide.PubMed
Jeffrey B Kreher, Jennifer B Schwartz
Sports Health. 2012 Mar;4(2):128-38. doi: 10.1177/1941738111434406.
CONTEXT: Fatigue and underperformance are common in athletes. Understanding overtraining syndrome (OTS) is helpful in the evaluation, management, and education of athletes. EVIDENCE ACQUISITION: Relevant articles in English were searched with OVID (1948-2011) and PubMed using the following keywords: overtraining syndrome, overtraining, overreaching, unexplained underperformance, staleness, pathophysiology, management, treatment, evaluation. Bibliographies were reviewed for additional resources. RESULTS: OTS appears to be a maladapted response to excessive exercise without adequate rest, resulting in perturbations of multiple body systems (neurologic, endocrinologic, immunologic) coupled with mood changes. Many hypotheses of OTS pathogenesis are reviewed, and a clinical approach to athletes with possible OTS (including history, testing, and prevention) is presented. CONCLUSIONS: OTS remains a clinical diagnosis with arbitrary definitions per the European College of Sports Science's position statement. History and, in most situations, limited serologies are helpful. However, much remains to be learned given that most past research has been on athletes with overreaching rather than OTS.
14Metabolic consequences of sleep and sleep loss.PubMed
Eve Van Cauter, Karine Spiegel, Esra Tasali, et al.
Sleep Med. 2008 Sep;9 Suppl 1(0 1):S23-8. doi: 10.1016/S1389-9457(08)70013-3.
Reduced sleep duration and quality appear to be endemic in modern society. Curtailment of the bedtime period to minimum tolerability is thought to be efficient and harmless by many. It has been known for several decades that sleep is a major modulator of hormonal release, glucose regulation and cardiovascular function. In particular, slow wave sleep (SWS), thought to be the most restorative sleep stage, is associated with decreased heart rate, blood pressure, sympathetic nervous activity and cerebral glucose utilization, compared with wakefulness. During SWS, the anabolic growth hormone is released while the stress hormone cortisol is inhibited. In recent years, laboratory and epidemiologic evidence have converged to indicate that sleep loss may be a novel risk factor for obesity and type 2 diabetes. The increased risk of obesity is possibly linked to the effect of sleep loss on hormones that play a major role in the central control of appetite and energy expenditure, such as leptin and ghrelin. Reduced leptin and increased ghrelin levels correlate with increases in subjective hunger when individuals are sleep restricted rather than well rested. Given the evidence, sleep curtailment appears to be an important, yet modifiable, risk factor for the metabolic syndrome, diabetes and obesity. The marked decrease in average sleep duration in the last 50 years coinciding with the increased prevalence of obesity, together with the observed adverse effects of recurrent partial sleep deprivation on metabolism and hormonal processes, may have important implications for public health.
15Evidence of High-Intensity Exercise on Lower Limb Functional Outcomes and Safety in Acute and Subacute Stroke Population: A Systematic Review.PubMed
Shi Min Mah, Alicia M Goodwill, Hui Chueng Seow, et al.
Int J Environ Res Public Health. 2022 Dec 22;20(1):153. doi: 10.3390/ijerph20010153.
This systematic review investigated the effects of high-intensity exercise (HIE) on lower limb (LL) function in acute and subacute stroke patients. A systematic electronic search was performed in PubMed, CINAHL and the Web of Science from inception to 30 June 2022. Outcomes examined included LL function and measures of activities of daily living such as the Barthel index, 6 min walk test (6MWT), gait speed and Berg balance scale (BBS), adverse events and safety outcomes. The methodological quality and the quality of evidence for each study was assessed using the PEDro scale and the Risk of Bias 2 tool (RoB 2). HIE was defined as achieving at least 60% of the heart rate reserve (HRR) or VO peak, 70% of maximal heart rate (HR), or attaining a score of 14 or more on the rate of perceived exertion Borg scale (6-20 rating scale). This study included randomized controlled trials (RCTs) which compared an intervention group of HIE to a control group of lower intensity exercise, or no intervention. All participants were in the acute (0-3 months) and subacute (3-6 months) stages of stroke recovery. Studies were excluded if they were not RCTs, included participants from a different stage of stroke recovery, or if the intervention did not meet the pre-defined HIE criteria. Overall, seven studies were included that used either high-intensity treadmill walking, stepping, cycling or overground walking exercises compared to either a low-intensity exercise ( = 4) or passive control condition ( = 3). Three studies reported significant improvements in 6MWT and gait speed performance, while only one showed improved BBS scores. No major adverse events were reported, although minor incidents were reported in only one study. This systematic review showed that HIE improved LL functional task performance, namely the 6MWT and gait speed. Previously, there was limited research demonstrating the efficacy of HIE early after stroke. This systematic review provides evidence that HIE may improve LL function with no significant adverse events report for stroke patients in their acute and subacute rehabilitation stages. Hence, HIE should be considered for implementation in this population, taking into account the possible benefits in terms of functional outcomes, as compared to lower intensity interventions.
16Four birds with one stone? Reparative, neuroplastic, cardiorespiratory, and metabolic benefits of aerobic exercise poststroke.PubMed
Michelle Ploughman, Liam P Kelly
Curr Opin Neurol. 2016 Dec;29(6):684-692. doi: 10.1097/WCO.0000000000000383.
PURPOSE OF REVIEW: Converging evidence from animal models of stroke and clinical trials suggests that aerobic exercise has effects across multiple targets. RECENT FINDINGS: The subacute phase is characterized by a period of heightened neuroplasticity when aerobic exercise has the potential to optimize recovery. In animals, low intensity aerobic exercise shrinks lesion size and reduces cell death and inflammation, beginning 24 h poststroke. Also in animals, aerobic exercise upregulates brain-derived neurotrophic factor near the lesion and improves learning. In terms of neuroplastic effects, clinical trial results are less convincing and have only examined effects in chronic stroke. Stroke patients demonstrate cardiorespiratory fitness levels below the threshold required to carry out daily activities. This may contribute to a 'neurorehabilitation ceiling' that limits capacity to practice at a high enough frequency and intensity to promote recovery. Aerobic exercise when delivered 2-5 days per week at moderate to high intensity beginning as early as 5 days poststroke improves cardiorespiratory fitness, dyslipidemia, and glucose tolerance. SUMMARY: Based on the evidence discussed and applying principles of periodization commonly used to prepare athletes for competition, we have created a model of aerobic training in subacute stroke in which training is delivered in density blocks (duration × intensity) matched to recovery phases.
17Training and overtraining: an overview and experimental results in endurance sports.PubMed
M J Lehmann, W Lormes, A Opitz-Gress, et al.
J Sports Med Phys Fitness. 1997 Mar;37(1):7-17.
Overtraining can be defined as "training-competition > > recovery imbalance", that is assumed to result in glycogen deficit, catabolic > anabolic imbalance, neuroendocrine imbalance, amino acid imbalance, and autonomic imbalance. Additional non-training stress factors and monotony of training exacerbate the risk of a resulting overtraining syndrome. Short-term overtraining called overreaching which can be seen as a normal part of athletic training, must be distinguished from long-term overtraining that can lead to a state described as burnout, staleness or overtraining syndrome. Persistent performance incompetence, persistent high fatigue ratings, altered mood state, increased rate of infections, and suppressed reproductive function have been described as key findings in overtraining syndrome. An increased risk of overtraining syndrome may be expected around 3 weeks of intensified/prolonged endurance training at a high training load level. Heavy training loads may apparently be tolerated for extensive periods of time if athletes take a rest day every week and use alternating hard and easy days of training. Persistent performance incompetence and high fatigue ratings may depend on impaired or inhibited transmission of ergotropic (catabolic) signals to target organs, such as: (I) decreased neuromuscular excitability, (II) inhibition of alpha-motoneuron activity (hypothetic), (III) decreased adrenal sensitivity to ACTH (cortisol release) and increased pituitary sensitivity to GHRH (GH release) resulting in a counter-regulatory shift to a more anabolic endocrine responsibility, (IV) decreased beta-adrenoreceptor density (sensitivity to catecholamines), (V) decreased intrinsic sympathetic activity, and (VI) intracellular protective mechanisms such as increased synthesis of heat-shock proteins (HSP 70) represent a complex strategy against an overload-dependent cellular damage.
18Morning versus Nocturnal Heart Rate and Heart Rate Variability Responses to Intensified Training in Recreational Runners.PubMed
Olli-Pekka Nuuttila, Heikki Kyröläinen, Veli-Pekka Kokkonen, et al.
Sports Med Open. 2024 Nov 6;10(1):120. doi: 10.1186/s40798-024-00779-5.
BACKGROUND: Resting heart rate (HR) and HR variability (HRV) are widely used parameters to assess cardiac autonomic nervous system function noninvasively. While resting assessments can be performed during sleep or after awakening, it would be relevant to know how interchangeable the results of these measurements are. This study aimed at examining the alignment between nocturnal and morning assessments during regular endurance training and in response to intensive training. A total of 24 recreational runners performed a 3-week baseline period (BL) and a 2-week overload (OL) period (Lucia's training impulse + 80%). Their running performance was assessed with a 3000-m running test after the BL and OL. The participants recorded daily their nocturnal HR and HRV (the natural logarithm of the root mean square of successive differences; LnRMSSD) with a photoplethysmography-based wrist device and performed an orthostatic test (2-min supine, 2-min standing) every morning with a chest-strap HR sensor. The HR and LnRMSSD segments that were analyzed from the nocturnal recordings included start value (SleepStart), end value (SleepEnd), first 4-h segment 30 min after detected sleep onset (Sleep4h), and full sleep time (SleepFull). The morning segments consisted of the last-minute average in both body positions. All segments were compared at BL and in response to the 3000-m test and OL. RESULTS: All nocturnal HR and LnRMSSD segments correlated with supine and standing segments at BL (r = 0.42 to 0.91, p < 0.05). After the 3000-m test, the HR increased and LnRMSSD decreased only in the SleepStart, Sleep4h, and SleepFull segments (p < 0.05). In response to the OL, the standing HR decreased (p < 0.01), while the LnRMSSD increased (p < 0.05) in all segments except for SleepStart. The Pearson correlations between relative changes in nocturnal and morning segments were - 0.11 to 0.72 (3000-m) and - 0.25 to 0.79 (OL). The OL response in Sleep4h HR and LnRMSSD correlated with the relative change in 3000-m time (r = 0.63, p = 0.001 and r=-0.50, p = 0.013, respectively). CONCLUSIONS: Nocturnal and morning HR and LnRMSSD correlated moderately or highly in the majority of cases during the BL, but their responses to intensive training were not similarly aligned, especially in LnRMSSD. The nocturnal segments seemed to be sensitive to physical loading, and their responses were associated with the performance-related training responses.
19Prolonged cortical silent period is related to poor fitness and fatigue, but not tumor necrosis factor, in Multiple Sclerosis.PubMed
Arthur R Chaves, Liam P Kelly, Craig S Moore, et al.
Clin Neurophysiol. 2019 Apr;130(4):474-483. doi: 10.1016/j.clinph.2018.12.015. Epub 2019 Feb 4.
OBJECTIVE: Poor fitness among people with Multiple Sclerosis (MS) aggravates disease symptoms. Whether low fitness levels accompany brain functioning changes is unknown. METHODS: MS patients (n = 82) completed a graded maximal exercise test, blood was drawn, and transcranial magnetic stimulation determined resting and active motor thresholds, motor evoked potential latency, and cortical silent period (CSP). RESULTS: Sixty-two percent of participants had fitness levels ranked below 10th percentile. Fitness was not associated with disability measured using the Expanded Disability Status Scale (EDSS). Regression analyses revealed that, cardiorespiratory fitness, when controlling for disease demographics, contributed 23.7% (p < 0.001) to the model explaining variance in CSP. Regression analysis using cardiorespiratory fitness and CSP as predictors showed that CSP alone explained 19.9% of variance in subjective fatigue (p = 0.002). Tumor necrosis factor was not associated with any variable. CONCLUSION: Low fitness was associated with longer CSP in MS. Longer CSP was, in turn, related to greater MS fatigue. SIGNIFICANCE: MS patients had extremely low levels of cardiorespiratory fitness. Poor fitness predicted longer CSP, a marker of greater intracortical inhibition, which was linked to MS fatigue. Future research should examine whether aerobic training could shorten CSP and potentially lessen inhibition of cortical networks.
20Fatigue after stroke: relationship to mobility, fitness, ambulatory activity, social support, and falls efficacy.PubMed
Kathleen M Michael, Jerilyn K Allen, Richard F Macko
Rehabil Nurs. 2006 Sep-Oct;31(5):210-7. doi: 10.1002/j.2048-7940.2006.tb00137.x.
Fatigue is common and persistent in stroke survivors, yet it is not known how mobility deficits, fitness, or other factors, such as social support, relate to fatigue severity, or whether subjective fatigue contributes to reduced ambulatory activity. The severity of fatigue in a sample of 53 community-dwelling subjects with chronic hemiparetic stroke was examined, and relationships among fatigue and mobility deficit severity, cardiovascular-metabolic fitness, ambulatory activity, social support, and self-efficacy for falls were identified. Measures included the Fatigue Severity Scale, timed 10-meter walks, the Berg Balance Scale, submaximal and peak VO2, total daily step activity derived from microprocessor-linked Step Activity Monitors, the Medical Outcomes Study Social Support Survey, and the Falls Efficacy Scale. Forty-six percent of the sample had severe fatigue. Fatigue showed no relationship to ambulatory activity. Fatigue severity was associated with the Berg Balance Scale (p < .01) and falls efficacy (p < .01), but not with cardiovascular fitness variables. Patients with elevated fatigue severity scores had lower social support (p < .05) and poorer falls efficacy scores (p < .05) than patients reporting less fatigue. Only falls efficacy was predictive of fatigue severity (r2 = 0.216, p < .01). Further studies are needed to evaluate whether rehabilitation strategies that include not only fitness and mobility interventions, but also social/behavioral and self-efficacy components, are associated with reduced fatigue and increased ambulation.
21Magnesium Matters: A Comprehensive Review of Its Vital Role in Health and Diseases.PubMed
Ghizal Fatima, Andrej Dzupina, Hekmat B Alhmadi, et al.
Cureus. 2024 Oct 13;16(10):e71392. doi: 10.7759/cureus.71392. eCollection 2024 Oct.
Magnesium (Mg), an essential mineral abundantly present within the human body, is intricately involved in a multitude of biochemical processes vital for maintaining health and overall well-being. This review aims to delve into the multifaceted impact of Mg on human health, exploring its physiological functions, dietary sources, and potential health implications of deficiency or insufficiency. Mg plays a pivotal role in various physiological processes, including energy metabolism, muscle contraction, protein synthesis, and DNA synthesis. It acts as a cofactor for more than 300 enzymatic reactions, facilitating the conversion of adenosine triphosphate (ATP) to adenosine diphosphate (ADP) for energy production. Moreover, Mg is essential for the proper functioning of ion channels, particularly calcium channels, influencing nerve transmission and muscle relaxation. Mg is naturally found in a wide array of foods, with green leafy vegetables, whole grains, nuts, seeds, and legumes being particularly rich sources. Additionally, certain fortified foods and dietary supplements provide supplemental Mg intake. Deficiency or insufficiency of mg can have profound implications for health. Inadequate mg levels have been associated with increased risks of various chronic diseases, including hypertension, type 2 diabetes, osteoporosis, and cardiovascular diseases. Furthermore, mg deficiency may manifest as symptoms such as muscle weakness, fatigue, tremors, and irregular heartbeat. Numerous studies have elucidated the relationship between mg intake and the risk of developing chronic diseases. For instance, epidemiological evidence suggests that higher mg intake is associated with a reduced risk of hypertension, possibly due to its vasodilatory effects and influence on blood pressure regulation mechanisms. Similarly, mg has been implicated in the pathophysiology of type 2 diabetes, with mg deficiency contributing to insulin resistance and impaired glucose metabolism. Furthermore, adequate mg intake is crucial for maintaining bone density and reducing the risk of osteoporosis, as mg plays a vital role in bone mineralization and bone health. Understanding the importance of mg in human physiology underscores the significance of ensuring adequate mg intake through diet or supplementation. Healthcare professionals play a critical role in educating individuals about the importance of incorporating mg-rich foods into their diets and considering mg supplementation when necessary, particularly for individuals at risk of deficiency or those with chronic diseases. Mg is an indispensable mineral with far-reaching implications for human health. Its involvement in various physiological processes underscores its importance in maintaining overall health and well-being. Ensuring adequate mg intake is essential for preventing deficiency-related health complications and reducing the risk of chronic diseases. Further research is warranted to elucidate the optimal strategies for mg supplementation and its potential therapeutic applications in disease prevention and management.
22Magnesium deficiency induces anxiety and HPA axis dysregulation: modulation by therapeutic drug treatment.PubMed
S B Sartori, N Whittle, A Hetzenauer, et al.
Neuropharmacology. 2012 Jan;62(1):304-12. doi: 10.1016/j.neuropharm.2011.07.027. Epub 2011 Aug 4.
Preclinical and some clinical studies suggest a relationship between perturbation in magnesium (Mg(2+)) homeostasis and pathological anxiety, although the underlying mechanisms remain largely unknown. Since there is evidence that Mg(2+) modulates the hypothalamic-pituitary adrenal (HPA) axis, we tested whether enhanced anxiety-like behaviour can be reliably elicited by dietary Mg(2+) deficiency and whether Mg(2+) deficiency is associated with altered HPA axis function. Compared with controls, Mg(2+) deficient mice did indeed display enhanced anxiety-related behaviour in a battery of established anxiety tests. The enhanced anxiety-related behaviour of Mg(2+) deficient mice was sensitive to chronic desipramine treatment in the hyponeophagia test and to acute diazepam treatment in the open arm exposure test. Mg(2+) deficiency caused an increase in the transcription of the corticotropin releasing hormone in the paraventricular hypothalamic nucleus (PVN), and elevated ACTH plasma levels, pointing to an enhanced set-point of the HPA axis. Chronic treatment with desipramine reversed the identified abnormalities of the stress axis. Functional mapping of neuronal activity using c-Fos revealed hyper-excitability in the PVN of anxious Mg(2+) deficient mice and its normalisation through diazepam treatment. Overall, the present findings demonstrate the robustness and validity of the Mg(2+) deficiency model as a mouse model of enhanced anxiety, showing sensitivity to treatment with anxiolytics and antidepressants. It is further suggested that dysregulations in the HPA axis may contribute to the hyper-emotionality in response to dietary induced hypomagnesaemia. This article is part of a Special Issue entitled 'Anxiety and Depression'.
23Effects of magnesium and potassium supplementation on insomnia and sleep hormones in patients with diabetes mellitus.PubMed
Sidra Khalid, Shahid Bashir, Riffat Mehboob, et al.
Front Endocrinol (Lausanne). 2024 Oct 29;15:1370733. doi: 10.3389/fendo.2024.1370733. eCollection 2024.
OBJECTIVES: Diabetes mellitus is a metabolic condition with hyperglycemia. Literature has shown a correlation between poor sleep quality and duration with an increased incidence of insomnia in diabetic individuals. The goal of this study was to determine the magnesium and potassium supplementation effect among diabetic individuals with insomnia. METHODS: A randomized controlled trial (single blind) was conducted on 320 patients with diabetes; after 2 months of follow-up, 290 patients completed the trial. The Insomnia Severity Index (ISI) was used to assess the severity and duration of insomnia, before and after the trial. Tablets containing supplements were prepared: placebo (T1), magnesium (Mg, T2), potassium (K, T3), and a combination of Mg and K (T4). Melatonin and cortisol (sleep hormones) were measured from blood (serum) using an enzyme-linked immunosorbent assay (ELISA), before and after the trial. RESULTS: The study included 93 (32.1%) male and 197 (67.9%) female participants. According to the analysis, there was a significant association between the treatment groups and ISI after the trial (post-trial), = 0.0001. Analysis showed that there was significant association between pre- and post-serum cortisol levels in treatment groups 2, 3, and 4 (T2, T3, and T4) as -values are 0.001, 0.001, and 0.001 respectively. Similar findings were observed for serum melatonin. CONCLUSIONS: The study revealed that magnesium, potassium, and magnesium and potassium combined had a significant effect on serum cortisol and melatonin levels (sleep hormones). In addition, supplementation significantly decreased the severity of insomnia among patients with diabetes by improving sleep duration.
24Acth-induced model of depression resistant to tricyclic antidepressants: Neuroendocrine and behavioral changes and influence of long-term magnesium administration.PubMed
Jelena Petrović, Dušanka Stanić, Zorica Bulat, et al.
Horm Behav. 2018 Sep;105:1-10. doi: 10.1016/j.yhbeh.2018.07.003. Epub 2018 Jul 19.
Magnesium (Mg), is not only a modulator of the glutamatergic NMDA receptors' affinity, it also prevents HPA axis hyperactivity, thus possibly being implicated in neurobiological features of mood disorders. Further uncovering of molecular mechanisms underlying magnesium's proposed effects is needed due to the recent shift in research of treatment resistant depression (TRD) towards glutamatergic pathways. Here, we applied Mg via drinking water for 28 days (50 mg/kg/day), in ACTH-treated rats, an established animal model of depression resistant to tricyclic antidepressants. Using this model in male rats we measured (1) changes in hippocampal neurogenesis and behavioral alterations, (2) adrenal hormones response to acute stress challenge and (3) levels of biometals involved in regulation of monoamines turnover in rat prefrontal cortex. Our results support beneficial behavioral impact of Mg in TRD model together with increased hippocampal neurogenesis and BDNF expression. Furthermore, Mg prevented ACTH-induced disruption in HPA axis function, by normalizing the levels of plasma ACTH, corticosterone and interleukin-6, and by increasing the peripheral release of adrenaline, noradrenaline and serotonin after the acute stress challenge. Finally, the influence on copper/zinc ratio suggested probable magnesium's involvement in monoamine turnover in PFC. Our findings provide further insights into the possible pathways implicated in the behavioral modulation effects of Mg, as well as its central and peripheral effects in ACTH-induced TRD model. Thus, further investigation of molecular signaling related to the glutamatergic transmission and role of Mg, could reveal prospects to novel treatment strategies that could be of particular importance for patients suffering from TRD.
25The effect of magnesium supplementation on primary insomnia in elderly: A double-blind placebo-controlled clinical trial.PubMed
Behnood Abbasi, Masud Kimiagar, Khosro Sadeghniiat, et al.
J Res Med Sci. 2012 Dec;17(12):1161-9.
BACKGROUND: Nearly 50% of older adults have insomnia, with difficulty in getting to sleep, early awakening, or feeling unrefreshed on waking. With aging, several changes occur that can place one at risk for insomnia, including age-related changes in various circadian rhythms, environmental and lifestyle changes, and decreased nutrients intake, absorption, retention, and utilization. The natural N-methyl-D-aspartic acid (NMDA) antagonist and GABA agonist, Mg(2+), seems to play a key role in the regulation of sleep. The objective of this study was to determine the efficacy of magnesium supplementation to improve insomnia in elderly. MATERIALS AND METHODS: A double-blind randomized clinical trial was conducted in 46 elderly subjects, randomly allocated into the magnesium or the placebo group and received 500 mg magnesium or placebo daily for 8 weeks. Questionnaires of insomnia severity index (ISI), physical activity, and sleep log were completed at baseline and after the intervention period. Anthropometric confounding factors, daily intake of magnesium, calcium, potassium, caffeine, calories form carbohydrates, and total calorie intake, were obtained using 24-h recall for 3 days. Blood samples were taken at baseline and after the intervention period for analysis of serum magnesium, renin, melatonin, and cortisol. Statistical analyses were performed using SPSS19 and P values < 0.05 were considered as statistically significant. RESULTS: No significant differences were observed in assessed variables between the two groups at the baseline. As compared to the placebo group, in the experimental group, dietary magnesium supplementation brought about statistically significant increases in sleep time (P = 0.002), sleep efficiency (P = 0.03), concentration of serum renin (P < 0.001), and melatonin (P = 0.007), and also resulted in significant decrease of ISI score (P = 0.006), sleep onset latency (P = 0.02) and serum cortisol concentration (P = 0.008). Supplementation also resulted in marginally between-group significant reduction in early morning awakening (P = 0.08) and serum magnesium concentration (P = 0.06). Although total sleep time (P = 0.37) did not show any significant between-group differences. CONCLUSION: Supplementation of magnesium appears to improve subjective measures of insomnia such as ISI score, sleep efficiency, sleep time and sleep onset latency, early morning awakening, and likewise, insomnia objective measures such as concentration of serum renin, melatonin, and serum cortisol, in elderly people.
26Oral Mg(2+) supplementation reverses age-related neuroendocrine and sleep EEG changes in humans.PubMed
Katja Held, I A Antonijevic, H Künzel, et al.
Pharmacopsychiatry. 2002 Jul;35(4):135-43. doi: 10.1055/s-2002-33195.
The process of normal aging is accompanied by changes in sleep-related endocrine activity. During aging, an increase in cortisol at its nadir and a decrease in renin and aldosterone concentration occur. In aged subjects, more time is spent awake and slow-wave sleep is reduced: there is a loss of sleep spindles and accordingly a loss of power in the sigma frequency range. Previous studies could show a close association between sleep architecture, especially slow-wave sleep, and activity in the glutamatergic and GABAergic system. Furthermore, recent studies could show that the natural N-methyl-D-aspartate (NMDA) antagonist and GABA(A) agonist Mg(2+) seems to play a key role in the regulation of sleep and endocrine systems such as the HPA system and renin-angiotensin-aldosterone system (RAAS). Therefore, we examined the effect of Mg(2+) in 12 elderly subjects (age range 60-80 years) on the sleep electroencephalogram (EEG) and nocturnal hormone secretion. A placebo-controlled, randomised cross-over design with two treatment intervals of 20 days duration separated by 2 weeks washout was used. Mg(2+) was administered as effervescent tablets in a creeping dose of 10 mmol and 20 mmol each for 3 days followed by 30 mmol for 14 days. At the end of each interval, a sleep EEG was recorded from 11 p.m. to 7 a.m. after one accommodation night. Blood samples were taken every 30 min between 8 p.m. and 10 p.m. and every 20 min between 10 p.m. and 7 a.m. to estimate ACTH, cortisol, renin and aldosterone plasma concentrations, and every hour for arginine-vasopressin (AVP) and angiotensin 11 (ATII) plasma concentrations. Mg(2+) led to a significant increase in slow wave sleep (16.5 +/- 20.4 min vs. 10.1 +/- 15.4 min, < or =0.05), delta power (47128.7 microV(2) +21417.7 microV(2) vs. 37862.1 microV(2) +/- 23241.7 microV(2), p < or =0.05) and sigma power (1923.0 microV(2) + 1111.3 microV(2) vs. 1541.0 microV(2) + 1134.5 microV(2), p< or =0.05 ). Renin increased (3.7 +/- 2.3 ng/ml x min vs. 2.3 +/- 1.0 ng/ml x min, p < 0.05) during the total night and aldosterone (3.6 +/- 4.7 ng/ml x min vs. 1.1 +/- 0.9 ng/ml x min, p < 0.05) in the second half of the night, whereas cortisol (8.3 +/- 2.4 pg/ml x min vs. 11.8 +/- 3.8 pg/ml x min, p < 0.01) decreased significantly and AVP by trend in the first part of the night. ACTH and ATII were not altered. Our results suggest that Mg(2+) partially reverses sleep EEG and nocturnal neuroendocrine changes occurring during aging. The similarities of the effect of Mg(2+) and that of the related electrolyte Li+ furthermore supports the possible efficacy of Mg(2+) as a mood stabilizer.
27Fibromyalgia and nutrition: Therapeutic possibilities?PubMed
Geir Bjørklund, Maryam Dadar, Salvatore Chirumbolo, et al.
Biomed Pharmacother. 2018 Jul;103:531-538. doi: 10.1016/j.biopha.2018.04.056. Epub 2018 Apr 24.
Fibromyalgia (FM) is a complex chronic condition of unknown etiology, characterized by deep and widespread pain, sleep problems, cognitive impairment, fatigue, and other well-known functional symptoms. Recently, it has been proposed that an imbalance of nutritive components, including essential metal ions and vitamins, might play a critical role in the development of FM. Muscle pain has been associated with deficiencies in amino acids, magnesium, selenium, vitamins B and D, as well as with the harmful effects of heavy metals, such as mercury, cadmium, and lead. Research indicates that patients deficient in certain essential nutrients may develop dysfunction of pain inhibitory mechanisms together with fatigue and other FM symptoms. Additionally, mercury and other toxic elements may interfere with the bioavailability of essential nutrients. This review examines the many effects of metals and vitamins in pain evaluation of FM patients. Dietary guidance is therefore critical for FM patients to help them in correcting a suboptimal or deficient intake of essential nutrients. When optimal levels of nutrition are achieved, pain levels are usually lowered. Additional research is recommended in the field of FM and nutrition to disclose further possible relationships.
28Oral magnesium supplementation for insomnia in older adults: a Systematic Review & Meta-Analysis.PubMed
Jasmine Mah, Tyler Pitre
BMC Complement Med Ther. 2021 Apr 17;21(1):125. doi: 10.1186/s12906-021-03297-z.
BACKGROUND: Magnesium supplementation is often purported to improve sleep; however, as both an over-the-counter sleep aid and a complementary and alternative medicine, there is limited evidence to support this assertion. The aim was to assess the effectiveness and safety of magnesium supplementation for older adults with insomnia. METHODS: A search was conducted in MEDLINE, EMBASE, Allied and Complementary Medicine, clinicaltrials.gov and two grey literature databases comparing magnesium supplementation to placebo or no treatment. Outcomes were sleep quality, quantity, and adverse events. Risk of bias and quality of evidence assessments were carried out using the RoB 2.0 and Grading of Recommendations Assessment, Development and Evaluation (GRADE) approaches. Data was pooled and treatment effects were quantified using mean differences. For remaining outcomes, a modified effects direction plot was used for data synthesis. RESULTS: Three randomized control trials (RCT) were identified comparing oral magnesium to placebo in 151 older adults in three countries. Pooled analysis showed that post-intervention sleep onset latency time was 17.36 min less after magnesium supplementation compared to placebo (95% CI - 27.27 to - 7.44, p = 0.0006). Total sleep time improved by 16.06 min in the magnesium supplementation group but was statistically insignificant. All trials were at moderate-to-high risk of bias and outcomes were supported by low to very low quality of evidence. CONCLUSION: This review confirms that the quality of literature is substandard for physicians to make well-informed recommendations on usage of oral magnesium for older adults with insomnia. However, given that oral magnesium is very cheap and widely available, RCT evidence may support oral magnesium supplements (less than 1 g quantities given up to three times a day) for insomnia symptoms.
29Short-Term Magnesium Therapy Alleviates Moderate Stress in Patients with Fibromyalgia: A Randomized Double-Blind Clinical Trial.PubMed
Nicolas Macian, Christian Dualé, Marion Voute, et al.
Nutrients. 2022 May 17;14(10):2088. doi: 10.3390/nu14102088.
Patients suffering from fibromyalgia often report stress and pain, with both often refractory to usual drug treatment. Magnesium supplementation seems to improve fibromyalgia symptoms, but the level of evidence is still poor. This study is a randomized, controlled, double-blind trial in fibromyalgia patients that compared once a day oral magnesium 100 mg (Chronomag, magnesium chloride technology formula) to placebo, for 1 month. The primary endpoint was the level of stress on the DASS-42 scale, and secondary endpoints were pain, sleep, quality of life, fatigue, catastrophism, social vulnerability, and magnesium blood concentrations. After 1 month of treatment, the DASS-42 score decreased in the magnesium and placebo groups but not significantly (21.8 ± 9.6 vs. 21.6 ± 10.8, respectively, = 0.930). Magnesium supplementation significantly reduced the mild/moderate stress subgroup (DASS-42 stress score: 22.1 ± 2.8 to 12.3 ± 7.0 in magnesium vs. 21.9 ± 11.9 to 22.9 ± 11.9 in placebo, = 0.003). Pain severity diminished significantly ( = 0.029) with magnesium while the other parameters were not significantly different between both groups. These findings show, for the first time, that magnesium improves mild/moderate stress and reduces the pain experience in fibromyalgia patients. This suggests that daily magnesium could be a useful treatment to improve the burden of disease of fibromyalgia patients and calls for a larger clinical trial.
30The effects of melatonin and magnesium in a novel supplement delivery system on sleep scores, body composition and metabolism in otherwise healthy individuals with sleep disturbances.PubMed
Rafael M Carlos, Catarina N Matias, Margarida L Cavaca, et al.
Chronobiol Int. 2024 Jun;41(6):817-828. doi: 10.1080/07420528.2024.2353225. Epub 2024 May 14.
The purpose of this study was to investigate the effects of a novel dietary supplement, including melatonin and magnesium, delivered via coffee pods on sleep quality, resting metabolic rate (RMR), and body composition in individuals with poor sleep quality disturbances. Using a double-blinded, randomized, crossover trial, we recruited 35 participants to a 4-week intervention with both supplements (1.9 mg melatonin + 200 mg elemental magnesium before sleep) and placebo conditions, considering a 7d washout period between treatments. The Pittsburgh Sleep Quality Index (PSQI) questionnaire was applied, RMR (kcal) was measured using indirect calorimetry (canopy ventilated open-circuit system) and body composition was assessed using dual-energy X-ray absorptiometry. Decreases in PSQI and anger - hostility scores, as well as in energy intake and fat mass, were observed ( < 0.05) for both conditions, from baseline to the end of each 4-week intervention. Differences between conditions were also observed for these parameters along with energy spent in activity, number of sedentary breaks, sleep efficiency, latency time, time in bed, total sleep time, awakening time, and movement index ( < 0.05) favouring the supplement condition. However, the final PSQI questionnaire scores still indicated poor sleep quality on average (PSQI > 5), in both conditions, with no changes regarding RMR. A melatonin-magnesium supplement, in a coffee pod format, showed improvements in sleep quality in otherwise healthy individuals with sleep disturbances, however PSQI questionnaire scores still indicated poor quality on average (PSQI > 5).
31Single prolonged stress decreases glutamate, glutamine, and creatine concentrations in the rat medial prefrontal cortex.PubMed
Dayan Knox, Shane A Perrine, Sophie A George, et al.
Neurosci Lett. 2010 Aug 9;480(1):16-20. doi: 10.1016/j.neulet.2010.05.052. Epub 2010 May 28.
Application of single prolonged stress (SPS) in rats induces changes in neuroendocrine function and arousal that are characteristic of post traumatic stress disorder (PTSD). PTSD, in humans, is associated with decreased neural activity in the prefrontal cortex, increased neural activity in the amygdala complex, and reduced neuronal integrity in the hippocampus. However, the extent to which SPS models these aspects of PTSD has not been established. In order to address this, we used high-resolution magic angle spinning proton magnetic resonance spectroscopy (HR-MAS (1)H MRS) ex vivo to assay levels of neurochemicals critical for energy metabolism (creatine and lactate), excitatory (glutamate and glutamine) and inhibitory (gamma amino butyric acid (GABA)) neurotransmission, and neuronal integrity (N-acetylaspartate (NAA)) in the medial prefrontal cortex (mPFC), amygdala complex, and hippocampus of SPS and control rats. Glutamate, glutamine, and creatine levels were decreased in the mPFC of SPS rats when compared to controls, which suggests decreased excitatory tone in this region. SPS did not alter the neurochemical profiles of either the hippocampus or amygdala. These data suggest that SPS selectively attenuates excitatory tone, without a disruption of neuronal integrity, in the mPFC.
32SONU20176289, a compound combining partial dopamine D(2) receptor agonism with specific serotonin reuptake inhibitor activity, affects neuroplasticity in an animal model for depression.PubMed
Adina T Michael-Titus, Monika Albert, Gregory J Michael, et al.
Eur J Pharmacol. 2008 Nov 19;598(1-3):43-50. doi: 10.1016/j.ejphar.2008.09.006. Epub 2008 Sep 17.
We investigated the efficacy of SONU20176289, a member of a group of novel phenylpiperazine derivatives with a mixed dopamine D(2) receptor partial agonist and specific serotonin reuptake inhibitor (SSRI) activity, in a chronic stress model of depression in male tree shrews. Animals were subjected to a 7-day period of psychosocial stress before treatment for 28 days with SONU20176289 (6 mg/kg/day, p.o.), during which stress was maintained. Stress reduced the in vivo brain concentrations of N-acetyl-aspartate, total creatine, and choline-containing compounds, as measured by localized proton magnetic resonance spectroscopy. Post mortem analyses revealed a reduced adult dentate cell proliferation and a decreased GluR2 expression in the prefrontal cortex. All these alterations were prevented by concomitant administration of SONU20176289. The results provide further support to the concept that antidepressant treatments may act by normalizing disturbed neuroplasticity, and indicate that combining dopamine D(2) receptor agonism with SSRI activity may serve as an effective tool in the treatment of depressive/anxiety syndromes.
33Therapeutic efficacy of atypical antipsychotic drugs by targeting multiple stress-related metabolic pathways.PubMed
H L Cai, P Jiang, Q Y Tan, et al.
Transl Psychiatry. 2017 May 16;7(5):e1130. doi: 10.1038/tp.2017.94.
Schizophrenia (SZ) is considered to be a multifactorial brain disorder with defects involving many biochemical pathways. Patients with SZ show variable responses to current pharmacological treatments of SZ because of the heterogeneity of this disorder. Stress has a significant role in the pathophysiological pathways and therapeutic responses of SZ. Atypical antipsychotic drugs (AAPDs) can modulate the stress response of the hypothalamic-pituitary-adrenal (HPA) axis and exert therapeutic effects on stress by targeting the prefrontal cortex (PFC) and hippocampus. To evaluate the effects of AAPDs (such as clozapine, risperidone and aripiprazole) on stress, we compared neurochemical profile variations in the PFC and hippocampus between rat models of chronic unpredictable mild stress (CUMS) for HPA axis activation and of long-term dexamethasone exposure (LTDE) for HPA axis inhibition, using an ultraperformance liquid chromatography-mass spectrometry (UPLC-MS/MS)-based metabolomic approach and a multicriteria assessment. We identified a number of stress-induced biomarkers comprising creatine, choline, inosine, hypoxanthine, uric acid, allantoic acid, lysophosphatidylcholines (LysoPCs), phosphatidylethanolamines (PEs), corticosterone and progesterone. Specifically, pathway enrichment and correlation analyses suggested that stress induces oxidative damage by disturbing the creatine-phosphocreatine circuit and purine pathway, leading to excessive membrane breakdown. Moreover, our data suggested that the AAPDs tested partially restore stress-induced deficits by increasing the levels of creatine, progesterone and PEs. Thus, the present findings provide a theoretical basis for the hypothesis that a combined therapy using adenosine triphosphate fuel, antioxidants and omega-3 fatty acids as supplements may have synergistic effects on the therapeutic outcome following AAPD treatment.
34Fueling the Firefighter and Tactical Athlete with Creatine: A Narrative Review of a Key Nutrient for Public Safety.PubMed
Drew E Gonzalez, Scott C Forbes, Annette Zapp, et al.
Nutrients. 2024 Sep 28;16(19):3285. doi: 10.3390/nu16193285.
Firefighters, tactical police officers, and warriors often engage in periodic, intermittent, high-intensity physical work in austere environmental conditions and have a heightened risk of premature mortality. In addition, tough decision-making challenges, routine sleep deprivation, and trauma exacerbate this risk. Therefore, identifying strategies to bolster these personnel's health and occupational performance is critical. Creatine monohydrate (CrM) supplementation may offer several benefits to firefighters and tactical athletes (e.g., police, security, and soldiers) due to its efficacy regarding physical performance, muscle, cardiovascular health, mental health, and cognitive performance. We conducted a narrative review of the literature with a focus on the benefits and application of creatine monohydrate among firefighters. Recent evidence demonstrates that CrM can improve anaerobic exercise capacity and muscular fitness performance outcomes and aid in thermoregulation, decision-making, sleep, recovery from traumatic brain injuries (TBIs), and mental health. Emerging evidence also suggests that CrM may confer an antioxidant/anti-inflammatory effect, which may be particularly important for firefighters and those performing tactical occupations exposed to oxidative and physiological stress, which can elicit systemic inflammation and increase the risk of chronic diseases. This narrative review highlights the potential applications of CrM for related tactical occupations, with a particular focus on firefighters, and calls for further research into these populations.
35How Microbes Affect Depression: Underlying Mechanisms via the Gut-Brain Axis and the Modulating Role of Probiotics.PubMed
Kazunori Suda, Kazunori Matsuda
Int J Mol Sci. 2022 Jan 21;23(3):1172. doi: 10.3390/ijms23031172.
Accumulating evidence suggests that the gut microbiome influences the brain functions and psychological state of its host via the gut-brain axis, and gut dysbiosis has been linked to several mental illnesses, including major depressive disorder (MDD). Animal experiments have shown that a depletion of the gut microbiota leads to behavioral changes, and is associated with pathological changes, including abnormal stress response and impaired adult neurogenesis. Short-chain fatty acids such as butyrate are known to contribute to the up-regulation of brain-derived neurotrophic factor (BDNF), and gut dysbiosis causes decreased levels of BDNF, which could affect neuronal development and synaptic plasticity. Increased gut permeability causes an influx of gut microbial components such as lipopolysaccharides, and the resultant systemic inflammation may lead to neuroinflammation in the central nervous system. In light of the fact that gut microbial factors contribute to the initiation and exacerbation of depressive symptoms, this review summarizes the current understanding of the molecular mechanisms involved in MDD onset, and discusses the therapeutic potential of probiotics, including butyrate-producing bacteria, which can mediate the microbiota-gut-brain axis.
36Microbiota and sleep: awakening the gut feeling.PubMed
Paromita Sen, Alicia Molinero-Perez, Kenneth J O'Riordan, et al.
Trends Mol Med. 2021 Oct;27(10):935-945. doi: 10.1016/j.molmed.2021.07.004. Epub 2021 Aug 4.
Various lifestyle and environmental factors are known to influence sleep. Increasingly, evidence points to a role for the microbiota in regulating brain and behaviour. This article explores how the microbiota-gut-brain axis affects sleep directly and indirectly. We summarize the possible molecular mechanisms underlying sleep-microbiome interactions and discuss how various factors interact with the gut microbiota to influence sleep. Furthermore, we present the current evidence of alterations of the microbiota-gut-brain axis in various sleep disorders and pathologies where comorbid sleep disturbances are common. Since manipulating the gut microbiota could potentially improve sleep, we outline ways in which this can be achieved.
37A review of dietary and microbial connections to depression, anxiety, and stress.PubMed
Andrew M Taylor, Hannah D Holscher
Nutr Neurosci. 2020 Mar;23(3):237-250. doi: 10.1080/1028415X.2018.1493808. Epub 2018 Jul 9.
Pre-clinical evidence suggests that the gastrointestinal microbiota contributes to mood and behavior disorders. Among humans, diet quality and patterns, which also impact the gastrointestinal microbiota, have been linked to depression, anxiety, and stress. This review summarizes findings from clinical studies using dietary intervention to improve depression, anxiety, or stress and the role the gastrointestinal microbiota may have in these disorders. A literature search was conducted using the keywords microbiome, microbiota, depression, anxiety, stress, diet, dietary pattern, diet quality, fiber, prebiotics, probiotics, and mood. Mood was improved by enhancing diet quality. Fructooligosaccharide and galactooligosaccharide improved anxiety and depression in participants consuming ≥ 5 g/day. Additionally, bifidobacteria were enriched in subjects consuming ≥ 5 g/day. Probiotic consumption improved psychological or biological measures of depression, anxiety, or stress in individuals predisposed to a mood disorder. Probiotics suppressed biological markers of stress in healthy individuals in a strain-dependent manner. High-quality diets, prebiotics, and probiotics may beneficially affect mood. Habitual diets rich in dietary fiber and omega-3-polyunsaturated fatty acids may be linked to reduced risk of developing symptoms of depression, anxiety, and stress; however, additional studies are necessary. Certain probiotics may enhance mood, but their influence on the gastrointestinal microbiota requires further investigation.
38Effects of Probiotics on Anxiety, Stress, Mood and Fitness of Badminton Players.PubMed
Razali Mohamed Salleh, Garry Kuan, Mohd Noorazlan Ab Aziz, et al.
Nutrients. 2021 May 24;13(6):1783. doi: 10.3390/nu13061783.
BACKGROUND: Reports of probiotic consumption on athletes' performance are debatable due to their equivocal results. There is a need for more evidence on the effects of probiotic intake on psychological state and fitness level. Thus, this study determined the effects of daily probiotic consumption on competitive anxiety, perceived stress and mood among university badminton players, besides their fitness like aerobic capacity, strength, speed, leg power and agility. METHODS: Thirty university badminton players aged from 19 to 22 years old were randomly divided equally into two groups, where the probiotic group (PG; = 15) received a drink that contained Shirota (3 × 10 CFU) and placebo group (CG; = 15) a placebo drink for six weeks. Anxiety, stress and mood levels were determined using the CSAI-2R, PSS and BRUMS questionnaires, respectively. Fitness levels were measured using by subjecting the players to 20-m shuttle runs (aerobic capacity), handgrips (muscular strength), vertical jumps (leg power), 40-m dash (speed) and T-test (agility). The Student's -test ( < 0.05) was used to determine the differences between PG and CG players. RESULTS: After six weeks, the anxiety and stress levels of PG players significantly decreased by 16% ( < 0.001) and 20% ( < 0.001), respectively, but there were no significant changes detected in CG players. Supplementation of probiotics also improved aerobic capacity in PG players by 5.9% ( < 0.001) but did not influence the speed, strength, leg power and agility. CONCLUSIONS: Probiotics supplementation showed improved aerobic capacity and relieve anxiety and stress. However, further studies need to be carried out to determine the mechanisms through which probiotic intake produces these effects.
39Probiotic Lactobacillus Plantarum 299v decreases kynurenine concentration and improves cognitive functions in patients with major depression: A double-blind, randomized, placebo controlled study.PubMed
Leszek Rudzki, Lucyna Ostrowska, Dariusz Pawlak, et al.
Psychoneuroendocrinology. 2019 Feb;100:213-222. doi: 10.1016/j.psyneuen.2018.10.010. Epub 2018 Oct 16.
BACKGROUND: Interactions between the digestive system and the brain functions have become in recent years an important field of psychiatric research. These multidirectional interactions take place in the so called microbiota-gut-brain axis and emerging scientific data indicate to the significant role of microbiota in the modulation of the central nervous system (CNS) including affective and cognitive functions. OBJECTIVE: An assessment of psychobiotic and immunomodulatory effects of probiotic bacteria Lactobacillus Plantarum 299v (LP299v) by measuring affective, cognitive functions and biochemical parameters in patients with MDD undergoing treatment with selective serotonin reuptake inhibitors (SSRI). DESIGN: Seventy nine patients with MDD were randomized and allocated to a double-blind, placebo-controlled trial. Participants received either a SSRI with the probiotic LP299v (n = 40) for a period of 8 weeks or a SSRI with the placebo of the probiotic (n = 39) for the same period. The severity of psychiatric symptoms was assessed using Hamilton Depression Rating Scale (HAM-D 17), Symptom Checklist (SCL-90) and Perceived Stress Scale (PSS-10). Cognitive functions were assessed using the Attention and Perceptivity Test (APT), Stroop Test parts A and B, Ruff Figural Fluency Test (RFFT), Trail Making Test (TMT) Parts A and B and the California Verbal Learning Test (CVLT). Biochemical parameters such as tryptophan (TRP), kynurenine (KYN), kynurenic acid (KYNA), 3-hydroxykynurenine (3HKYN), anthranilic acid (AA), 3-hydroxy anthranilic acid (3HAA), tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), interleukin 1-beta (IL-1b) and cortisol plasma concentrations were measured. RESULTS: Sixty participants finished the study and were analyzed: 30 participants in the LP299v group and 30 participants in the placebo group. There was an improvement in APT and in CVLT total recall of trials 1-5 in the LP299v group compared with the placebo between baseline and after 8 weeks of intervention. There was a significant decrease in KYN concentration in the LP299v group compared to the placebo group. We also observed significant increase in 3HKYN:KYN ratio in the LP299v group compared with the placebo group. Additionally, Repeated Measures ANOVA revealed a significant effect of interaction of Treatment x time for AA concentration. However, results of post hoc analysis did not reach statistical significance in neither probiotic nor placebo group. There were no significant changes of TNF-α, IL-6 and IL-1b and cortisol concentrations in neither probiotic nor placebo groups. CONCLUSIONS: Augmentation of SSRI treatment with probiotic bacteria Lactobacillus Plantarum 299v improved cognitive performance and decreased KYN concentration in MDD patients. Decreased KYN concentration could contribute to the improvement of cognitive functions in the LP299v group compared to the placebo group. To our knowledge results of this study are the first evidence of improvement of cognitive functions in MDD patients due to probiotic bacteria and this is the first evidence of decreased KYN concentration in MDD patients due to probiotic bacteria.
40Probiotics, prebiotics and postbiotics for better sleep quality: a narrative review.PubMed
J E Haarhuis, A Kardinaal, G A M Kortman
Benef Microbes. 2022 Aug 3;13(3):169-182. doi: 10.3920/BM2021.0122. Epub 2022 Jul 11.
There is a growing prevalence of sleep problems and insomnia worldwide, urging the development of new treatments to tackle this increase. Several studies have suggested that the gut microbiome might influence sleep quality. The gut microbiome affects the host's health via the production of metabolites and compounds with neuroactive and immunomodulatory properties, which include short-chain fatty acids, secondary bile acids and neurotransmitters. Several of these metabolites and compounds are independently known as wakefulness-promoting (serotonin, epinephrine, dopamine, orexin, histamine, acetylcholine, cortisol) or sleep-promoting (gamma-aminobutyric acid, melatonin). The primary aim of this review was to evaluate the potential of pro-, pre- and postbiotic treatments to improve sleep quality. Additionally, we aimed to evaluate whether each of the treatments could ameliorate stress and anxiety, which are known to bidirectionally correlate with sleep problems. Lastly, we provided a mechanistic explanation for our findings. A literature search was conducted using PubMed, Scopus, Web of Science, and Google Scholar to compare all human trials that met our inclusion criteria and were published before November 2021. We furthermore discussed relevant findings from animal experiments to provide a mechanistic insight. While several studies found that sleep latency, sleep length, and cortisol levels improved after pro-, pre- or postbiotic treatment, others did not show any significant improvements for sleep quality, stress, or anxiety. These discrepancies can be explained by between-study variations in study designs, study populations, treatments, type and level of distress, and sex differences. We conclude that the trials discussed provide some evidence for prebiotics, postbiotics, and traditional probiotics, such as those belonging to lactobacilli and bifidobacteria, to improve sleep quality and stress, but stronger evidence might be found in the future after implementing the methodological adjustments that are suggested in this review.
41Dietary Supplements for Health, Adaptation, and Recovery in Athletes.PubMed
Eric S Rawson, Mary P Miles, D Enette Larson-Meyer
Int J Sport Nutr Exerc Metab. 2018 Mar 1;28(2):188-199. doi: 10.1123/ijsnem.2017-0340. Epub 2018 Feb 19.
Some dietary supplements are recommended to athletes based on data that supports improved exercise performance. Other dietary supplements are not ergogenic per se, but may improve health, adaptation to exercise, or recovery from injury, and so could help athletes to train and/or compete more effectively. In this review, we describe several dietary supplements that may improve health, exercise adaptation, or recovery. Creatine monohydrate may improve recovery from and adaptation to intense training, recovery from periods of injury with extreme inactivity, cognitive processing, and reduce severity of or enhance recovery from mild traumatic brain injury (mTBI). Omega 3-fatty acid supplementation may also reduce severity of or enhance recovery from mTBI. Replenishment of vitamin D insufficiency or deficiency will likely improve some aspects of immune, bone, and muscle health. Probiotic supplementation can reduce the incidence, duration, and severity of upper respiratory tract infection, which may indirectly improve training or competitive performance. Preliminary data show that gelatin and/or collagen may improve connective tissue health. Some anti-inflammatory supplements, such as curcumin or tart cherry juice, may reduce inflammation and possibly delayed onset muscle soreness (DOMS). Beta-hydroxy beta-methylbutyrate (HMB) does not consistently increase strength and/or lean mass or reduce markers of muscle damage, but more research on recovery from injury that includes periods of extreme inactivity is needed. Several dietary supplements, including creatine monohydrate, omega 3-fatty acids, vitamin D, probiotics, gelatin, and curcumin/tart cherry juice could help athletes train and/or compete more effectively.
42"Do probiotics mitigate GI-induced inflammation and perceived fatigue in athletes? A systematic review".PubMed
R P Kearns, J S G Dooley, M Matthews, et al.
J Int Soc Sports Nutr. 2024 Dec;21(1):2388085. doi: 10.1080/15502783.2024.2388085. Epub 2024 Aug 28.
BACKGROUND: Fatigue and gastrointestinal (GI) distress are common among athletes with an estimated 30-90% of athletes participating in marathons, triathlons, or similar events experiencing GI complaints. Intense exercise can lead to increased intestinal permeability, potentially allowing members of the gut microbiota to permeate into the bloodstream, resulting in an inflammatory response and cascade of performance-limiting outcomes. Probiotics, through their capacity to regulate the composition of the gut microbiota, may act as an adjunctive therapy by enhancing GI and immune function while mitigating inflammatory responses. This review investigates the effectiveness of probiotic supplementation on fatigue, inflammatory markers, and exercise performance based on randomized controlled trials (RCTs). METHODS: This review follows the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines and PICOS (Population, Intervention, Comparison, Outcome, Study design) framework. A comprehensive search was conducted in Sportdiscus, PubMed, and Scopus databases, and the screening of titles, abstracts, and full articles was performed based on pre-defined eligibility criteria. Of the 3505 records identified, 1884 were screened using titles and abstracts, of which 450 studies were selected for full-text screening. After final screening, 13 studies met the eligibility criteria and were included for review. The studies contained 513 participants, consisting of 351 males and 115 females, however, two studies failed to mention the sex of the participants. Among the participants, 246 were defined as athletes, while the remaining participants were classified as recreationally active ( = 267). All trials were fully described and employed a double- or triple-blind placebo-controlled intervention using either a single probiotic strain or a multi-strain synbiotic (containing both pro- and pre-biotics). RESULTS: This review assesses the effects of daily probiotic supplementation, ranging from 13 to 90 days, on physical performance and physiological markers in various exercise protocols. Ten studies reported improvements in various parameters, such as, enhanced endurance performance, improved anxiety and stress levels, decreased GI symptoms, and reduced upper respiratory tract infections (URTI). Moreover, despite no improvements in maximal oxygen uptake (VO), several studies demonstrated that probiotic supplementation led to amelioration in lactate, creatine kinase (CK), and ammonia concentrations, suggesting beneficial effects on mitigating exercise-induced muscular stress and damage. CONCLUSION: Probiotic supplementation, specifically at a minimum dosage of 15 billion CFUs daily for a duration of at least 28 days, may contribute to the reduction of perceived or actual fatigue.
43Creatine as nutritional supplementation and medicinal product.PubMed
G Benzi, A Ceci
J Sports Med Phys Fitness. 2001 Mar;41(1):1-10.
Because of assumed ergogenic effects, the creatine administration has become popular practice among subjects participating in different sports. Appropriate creatine monohydrate dosage may be considered a medicinal product since, in accordance with the Council Directive 65/65/EEC, any substance which may be administered with a view to restoring, correcting or modifying physiological functions in humans beings is considered a medicinal product. Thus, quality, efficacy and safety must characterise the substance. In addition, the European Court of Justice has held that a product which is recommended or described as having preventive or curative properties is a medicinal product even if it is generally considered as a foodstuff and even if it has no known therapeutic effect in the present state of scientific knowledge. In biochemical terms, creatine administration increases creatine and phosphocreatine muscle concentration, allowing for an accelerated rate of ATP synthesis. In thermodynamics terms, creatine stimulates the creatine-creatine kinase-phosphocreatine circuit, which is related to the mitochondrial function as a highly organised system for the control of the subcellular adenylate pool. In pharmacokinetics terms, creatine entry into skeletal muscle is initially dependent on the extracellular concentration, but the creatine transport is subsequently downregulated. In pharmacodynamics terms, the creatine enhances the possibility to maintain power output during brief periods of high-intensity exercises. In spite of uncontrolled daily dosage and long-term administration, no researches on creatine monohydrate safety in humans were set up by standardised protocols of clinical pharmacology and toxicology, as currently occurs in phases I and II for products for human use. More or less documented side effects induced by creatine monohydrate are weight gain; influence on insulin production; feedback inhibition of endogenous creatine synthesis; long-term damages on renal function. A major point that related to the quality of creatine monohydrate products is the amount of creatine ingested in relation to the amount of contaminants present. During the industrial production of creatine monohydrate from sarcosine and cyanamide, variable amounts of contaminants (dicyandiamide, dihydrotriazines, creatinine, ions) are generated and, thus, their tolerable concentrations (ppm) must be defined and made consumers known. Furthermore, because sarcosine could originate from bovine tissues, the risk of contamination with prion of bovine spongiform encephalopathy (BSE or mad-cow disease) can t be excluded. Thus, French authorities forbade the sale of products containing creatine. Creatine, as other nutritional factors, can be used either at supplementary or therapeutic levels as a function of the dose. Supplementary doses of nutritional factors usually are of the order of the daily turnover, while therapeutic ones are three or more times higher. In a subject of 70 kg with a total creatine pool of 120 g, the daily turnover is approximately of 2 g. Thus, in healthy subjects nourished with fat-rich, carbohydrate, protein-poor diet and participating in a daily recreational sport, the oral creatine monohydrate supplementation should be of the order of the daily turnover, i.e., less than 2.5-3 g per day, bringing the gastrointestinal absorption to account. In healthy athletes submitted daily to high-intensity strength or sprint training, the maximal oral creatine monohydrate supplementation should be of the order of two times the daily turnover, i.e., less than 5-6 g per day for less than two weeks, and the creatine monohydrate supplementation should be taken under appropriate medical supervision. The oral administration of more that 6 g per day of creatine monohydrate should be considered as a therapeutic intervention and should be prescribed by physicians only in the cases of suspected or proven deficiency, or in conditions of severe stress and/or injury. The incorporation of creatine into the medicinal product class is supported also by the use in pathological conditions, e.g., some mitochondrial cytopathies, the guanidinoacetate methyltransferase deficiency, etc.
44Stress and the gut: pathophysiology, clinical consequences, diagnostic approach and treatment options.PubMed
Peter C Konturek, T Brzozowski, S J Konturek
J Physiol Pharmacol. 2011 Dec;62(6):591-9.
Stress, which is defined as an acute threat to homeostasis, shows both short- and long-term effects on the functions of the gastrointestinal tract. Exposure to stress results in alterations of the brain-gut interactions ("brain-gut axis") ultimately leading to the development of a broad array of gastrointestinal disorders including inflammatory bowel disease (IBD), irritable bowel syndrome (IBS) and other functional gastrointestinal diseases, food antigen-related adverse responses, peptic ulcer and gastroesophageal reflux disease (GERD). The major effects of stress on gut physiology include: 1) alterations in gastrointestinal motility; 2) increase in visceral perception; 3) changes in gastrointestinal secretion; 4) increase in intestinal permeability; 5) negative effects on regenerative capacity of gastrointestinal mucosa and mucosal blood flow; and 6) negative effects on intestinal microbiota. Mast cells (MC) are important effectors of brain-gut axis that translate the stress signals into the release of a wide range of neurotransmitters and proinflammatory cytokines, which may profoundly affect the gastrointestinal physiology. IBS represents the most important gastrointestinal disorder in humans, and is characterized by chronic or recurrent pain associated with altered bowel motility. The diagnostic testing for IBS patients include routine blood tests, stool tests, celiac disease serology, abdominal sonography, breath testing to rule out carbohydrate (lactose, fructose, etc.) intolerance and small intestinal bacterial overgrowth. Colonoscopy is recommended if alarming symptoms are present or to obtain colonic biopsies especially in patients with diarrhoea predominant IBS. The management of IBS is based on a multifactorial approach and includes pharmacotherapy targeted against the predominant symptom, behavioural and psychological treatment, dietary alterations, education, reassurance and effective patient-physician relationship. When evaluating for the stress-induced condition in the upper GI tract, the diagnostic testing includes mainly blood tests and gastroscopy to rule out GERD and peptic ulcer disease. The therapy for these conditions is mainly based on the inhibition of gastric acid by proton pump inhibitors and eradication of Helicobacter pylori-infection. Additionally, melatonin an important mediator of brain gut axis has been shown to exhibit important protective effects against stress-induced lesions in the gastrointestinal tract. Finally, probiotics may profoundly affect the brain-gut interactions ("microbiome-gut-brain axis") and attenuate the development of stress-induced disorders in both the upper and lower gastrointestinal tract. Further studies on the brain-gut axis are needed to open new therapeutic avenues in the future.
45Probiotics: Potential novel therapeutics for microbiota-gut-brain axis dysfunction across gender and lifespan.PubMed
Shikha Snigdha, Kevin Ha, Paul Tsai, et al.
Pharmacol Ther. 2022 Mar;231:107978. doi: 10.1016/j.pharmthera.2021.107978. Epub 2021 Sep 4.
Probiotics are live microorganisms, which when administered in adequate amounts, present a health benefit for the host. While the beneficial effects of probiotics on gastrointestinal function are generally well recognized, new animal research and clinical studies have found that alterations in gut microbial communities can have a broad range of effects throughout the body. Non-intestinal sites impacted include the immune, endocrine, cardiovascular and the central nervous system (CNS). In particular, there has been a growing interest and appreciation about the role that gut microbiota may play in affecting CNS-related function through the 'microbiota-gut-brain axis'. Emerging evidence suggests potential therapeutic benefits of probiotics in several CNS conditions, such as anxiety, depression, autism spectrum disorders and Parkinson's disease. There may also be some gender-specific variances in terms of probiotic mediated effects, with the gut microbiota shaping and being concurrently molded by the hormonal environment governing differences between the sexes. Probiotics may influence the ability of the gut microbiome to affect a variety of biological processes in the host, including neurotransmitter activity, vagal neurotransmission, generation of neuroactive metabolites and inflammatory response mediators. Some of these may engage in cross talk with host sex hormones, such as estrogens, which could be of relevance in relation to their effects on stress response and cognitive health. This raises the possibility of gender-specific variation with regards to the biological action of probiotics, including that on the endocrine and central nervous systems. In this review we aim to describe the current understanding in relation to the role and use of probiotics in microbiota-gut-brain axis-related dysfunction. Furthermore, we will address the conceptualization and classification of probiotics in the context of gender and lifespan as well as how restoring gut microbiota composition by clinical or dietary intervention can help in supporting health outcomes other than those related to the gastrointestinal tract. We also evaluate how these new learnings may impact industrial effort in probiotic research and the discovery and development of novel and more personalized, condition-specific, beneficial probiotic therapeutic agents.
46The Power of Psychobiotics in Depression: A Modern Approach through the Microbiota-Gut-Brain Axis: A Literature Review.PubMed
Angela Dziedzic, Karina Maciak, Katarzyna Bliźniewska-Kowalska, et al.
Nutrients. 2024 Apr 4;16(7):1054. doi: 10.3390/nu16071054.
The microbiota-gut-brain (MGB) axis is a complex communication network linking the gut, microbiota, and brain, influencing various aspects of health and disease. Dysbiosis, a disturbance in the gut microbiome equilibrium, can significantly impact the MGB axis, leading to alterations in microbial composition and function. Emerging evidence highlights the connection between microbiota alterations and neurological and psychiatric disorders, including depression. This review explores the potential of psychobiotics in managing depressive disorders, emphasizing their role in restoring microbial balance and influencing the MGB axis. Psychobiotics exhibit positive effects on the intestinal barrier, immune response, cortisol levels, and the hypothalamic-pituitary-adrenal (HPA) axis. Studies suggest that probiotics may serve as an adjunct therapy for depression, especially in treatment-resistant cases. This review discusses key findings from studies on psychobiotics interventions, emphasizing their impact on the gut-brain axis and mental health. The increasing acceptance of the expanded concept of the MGB axis underscores the importance of microorganisms in mental well-being. As our understanding of the microbiome's role in health and disease grows, probiotics emerge as promising agents for addressing mental health issues, providing new avenues for therapeutic interventions in depressive disorders.
47Exercise-induced stress behavior, gut-microbiota-brain axis and diet: a systematic review for athletes.PubMed
Allison Clark, Núria Mach
J Int Soc Sports Nutr. 2016 Nov 24;13:43. doi: 10.1186/s12970-016-0155-6. eCollection 2016.
Fatigue, mood disturbances, under performance and gastrointestinal distress are common among athletes during training and competition. The psychosocial and physical demands during intense exercise can initiate a stress response activating the sympathetic-adrenomedullary and hypothalamus-pituitary-adrenal (HPA) axes, resulting in the release of stress and catabolic hormones, inflammatory cytokines and microbial molecules. The gut is home to trillions of microorganisms that have fundamental roles in many aspects of human biology, including metabolism, endocrine, neuronal and immune function. The gut microbiome and its influence on host behavior, intestinal barrier and immune function are believed to be a critical aspect of the brain-gut axis. Recent evidence in murine models shows that there is a high correlation between physical and emotional stress during exercise and changes in gastrointestinal microbiota composition. For instance, induced exercise-stress decreased cecal levels of spp and increased which have well defined roles in intestinal mucus degradation and immune function. Diet is known to dramatically modulate the composition of the gut microbiota. Due to the considerable complexity of stress responses in elite athletes (from leaky gut to increased catabolism and depression), defining standard diet regimes is difficult. However, some preliminary experimental data obtained from studies using probiotics and prebiotics studies show some interesting results, indicating that the microbiota acts like an endocrine organ (e.g. secreting serotonin, dopamine or other neurotransmitters) and may control the HPA axis in athletes. What is troubling is that dietary recommendations for elite athletes are primarily based on a low consumption of plant polysaccharides, which is associated with reduced microbiota diversity and functionality (e.g. less synthesis of byproducts such as short chain fatty acids and neurotransmitters). As more elite athletes suffer from psychological and gastrointestinal conditions that can be linked to the gut, targeting the microbiota therapeutically may need to be incorporated in athletes' diets that take into consideration dietary fiber as well as microbial taxa not currently present in athlete's gut.
48DR7 alleviates stress and anxiety in adults: a randomised, double-blind, placebo-controlled study.PubMed
H X Chong, N A A Yusoff, Y-Y Hor, et al.
Benef Microbes. 2019 Apr 19;10(4):355-373. doi: 10.3920/BM2018.0135. Epub 2019 Mar 18.
Probiotics have been reported to exert beneficial effects along the gut-brain axis. This randomised, double-blind and placebo-controlled human study aimed to evaluate such properties of DR7 and its accompanying mechanisms in stressed adults. One hundred and eleven (n=111; DR7 n=56, placebo n=55) stressed adults were recruited based on moderate stress levels using the PSS-10 questionnaire. The consumption of DR7 (1×10 cfu/day) for 12 weeks reduced symptoms of stress (=0.024), anxiety (=0.001), and total psychological scores (=0.022) as early as 8 weeks among stressed adults compared to the placebo group as assessed by the DASS-42 questionnaire. Plasma cortisol level was reduced among DR7 subjects as compared to the placebo, accompanied by reduced plasma pro-inflammatory cytokines, such as interferon-γ and transforming growth factor-α and increased plasma anti-inflammatory cytokines, such as interleukin 10 (<0.05). DR7 better improved cognitive and memory functions in normal adults (>30 years old), such as basic attention, emotional cognition, and associate learning (<0.05), as compared to the placebo and young adults (<30 years old). The administration of DR7 enhanced the serotonin pathway, as observed by lowered expressions of plasma dopamine β-hydroxylase (DBH), tyrosine hydroxylase (TH), indoleamine 2,3-dioxygenase and tryptophan 2,3-dioxygenase accompanied by increased expressions of tryptophan hydroxylase-2 and 5-hydroxytryptamine receptor-6, while stabilising the dopamine pathway as observed via stabilised expressions of TH and DBH over 12 weeks as compared to the placebo (<0.05). Our results indicated that DR7 fulfil the requirement of a probiotic strain as per recommendation of FAO/WHO and could be applicable as a natural strategy to improve psychological functions, cognitive health and memory in stressed adults.
49Levilactobacillus brevis SG031 modulates mood-related behaviors and attenuates stress-related sleep disturbance and autonomic dysfunction via gut microbiota modulation in Wistar-Kyoto rats.PubMed
Chieh-Wen Chen, Hung-Chang Chen, Sheng-Chieh She, et al.
Life Sci. 2024 Aug 15;351:122804. doi: 10.1016/j.lfs.2024.122804. Epub 2024 Jun 7.
AIMS: The probiotic bacterium Levilactobacillus brevis (L. brevis) has been proposed as a potential solution to manage mood disorders and alleviate stress-related sleep disturbances. However, the underlying mechanisms of its effects have not been fully elucidated. The aim of this study was to explore the impact and potential mechanisms of L. brevis SG031 supplementation on anxiety/depression-like behaviors and stress-induced changes in sleep patterns and sleep-related autonomic function. MAIN METHODS: Male Wistar-Kyoto rats were administered low, medium, or high doses of L. brevis SG031 or a vehicle for 4 weeks, followed by behavioral tests to evaluate anxiety and depression. After an additional 2 weeks of SG031 or vehicle administration, a cage-exchange paradigm was performed with 24-hour physiological signal measurements under different stress conditions. Fecal samples were collected to construct a 16S rRNA library and assess fecal short-chain fatty acids (SCFAs). KEY FINDINGS: High-dose SG031 administration yielded reduced depression-like responses and enhanced social interaction in behavioral tests. It also exhibited a protective effect against stress-induced sleep disturbance characterized by decreased sleep time, increased awake time, and autonomic dysfunction during sleep. Fecal examination indicated that high-dose SG031 administration exerted beneficial effects on gut health by maintaining the gut microbial abundance, preserving stability of the microbial composition, and enriching the gut with SCFAs, which were associated with improvements in sleep and autonomic function. SIGNIFICANCE: These findings collectively underscore the multifaceted potential of SG031 in addressing mental health and stress-related sleep challenges through the modulation of the gut microbiota.
50Psychobiotics in mental health, neurodegenerative and neurodevelopmental disorders.PubMed
Li-Hao Cheng, Yen-Wenn Liu, Chien-Chen Wu, et al.
J Food Drug Anal. 2019 Jul;27(3):632-648. doi: 10.1016/j.jfda.2019.01.002. Epub 2019 Feb 10.
Psychobiotics are a group of probiotics that affect the central nervous system (CNS) related functions and behaviors mediated by the gut-brain-axis (GBA) via immune, humoral, neural, and metabolic pathways to improve not only the gastrointestinal (GI) function but also the antidepressant and anxiolytic capacity. As a novel class of probiotics, the application of psychobiotics has led researchers to focus on a new area in neuroscience. In the past five years, some psychobiotics strains were reported to inhibit inflammation and decreased cortisol levels, resulting in an amelioration of the symptoms of anxiety and depression. Psychobiotics are efficacious in improving neurodegenerative and neurodevelopmental disorders, including autism spectrum disorder (ASD), Parkinson's disease (PD) and Alzheimer's disease (AD). Use of psychobiotics can improve GI function, ASD symptoms, motor functions of patients with PD and cognition in patients with AD. However, the evidence for the effects of psychobiotics on mental and neurological conditions/disorders remains limited. Further studies of psychobiotics are needed in order to determine into their effectiveness and mechanism as treatments for various psychiatric disorders in the future.
51subsp. Reduces Perceived Psychological Stress in Healthy Adults: An Exploratory Clinical Trial.PubMed
Marcus Boehme, Noëla Rémond-Derbez, Clara Lerond, et al.
Nutrients. 2023 Jul 13;15(14):3122. doi: 10.3390/nu15143122.
Emerging science shows that probiotic intake may impact stress and mental health. We investigated the effect of a 6-week intervention with (1 × 10 CFU/daily) on stress-related psychological and physiological parameters in 45 healthy adults with mild-to-moderate stress using a randomized, placebo-controlled, two-arm, parallel, double-blind design. The main results showed that supplementation with the probiotic significantly reduced the perceived stress and improved the subjective sleep quality score compared to placebo. Comparing the two groups, momentary subjective assessments concomitant to the Maastricht Acute Stress Test revealed a lower amount of pain experience in the probiotic group and a higher amount of relief at the end of the procedure in the placebo group, reflected by higher scores in the positive affect state. The awakening of the salivary cortisol response was not affected by the intervention, yet the reduction observed in the salivary cortisol stress response post-intervention was higher in the placebo group than the probiotic group. Multivariate analysis further indicated that a reduction in perceived stress correlated with a reduction in anxiety, in depression, and in the cortisol awakening response after the 6-week intervention. This exploratory trial provides promising insights into to reduce perceived stress in a healthy population and supports the potential of nutritional solutions including probiotics to improve mental health.
52Lactobacillus plantarum MTCC 9510 supplementation protects from chronic unpredictable and sleep deprivation-induced behaviour, biochemical and selected gut microbial aberrations in mice.PubMed
J Dhaliwal, D P Singh, S Singh, et al.
J Appl Microbiol. 2018 Jul;125(1):257-269. doi: 10.1111/jam.13765. Epub 2018 May 8.
AIM: Here, we evaluated any beneficial effects of a potential probiotic bacterial strain (Lactobacillus plantarum MTCC 9510) in two different stress paradigms in mice. METHODS AND RESULTS: Lactobacillus plantarum MTCC 9510 (2 × 10 CFU per mice) was supplemented to male Swiss albino mice either subjected to chronic unpredictable mild stress or sleep deprivation (SD) stress. Various behavioural and biochemical tests along with selected gut bacterial abundances were determined. Lactobacillus plantarum MTCC 9510 supplementation prevented stress-induced behavioural despair (depression, anxiety, learning and memory, stereotypic behaviour), oxidative stress markers and inflammatory cytokines in brain and serum. Its supplementation also improved gut and blood brain barrier integrity. It also affected caecal short-chain fatty acids along with the promotion of Lactobacillus sp. and reduction in Enterobacteriaceae abundances. We also observed that two different stresses variably affected various behavioural and biochemical changes but L. plantarum MTCC 9510 supplementation most effectively prevented all these changes. CONCLUSION: We provide evidence that positive modulation of the selected beneficial gut microbial population could serve as a viable strategy to neutralize day-to-day and SD stress-induced pathological alterations. SIGNIFICANCE AND IMPACT OF THE STUDY: Therapeutic potential of this/other probiotic strains in tackling the deleterious neurobiological effects on exposure to various stress-related conditions can be explored.
53Not Only Protein: Dietary Supplements to Optimize the Skeletal Muscle Growth Response to Resistance Training: The Current State of Knowledge.PubMed
Antonio Paoli, Giuseppe Cerullo, Antonino Bianco, et al.
J Hum Kinet. 2024 Apr 15;91(Spec Issue):225-244. doi: 10.5114/jhk/18666. eCollection 2024 Mar.
Regarding skeletal muscle hypertrophy, resistance training and nutrition, the most often discussed and proposed supplements include proteins. Although, the correct amount, quality, and daily distribution of proteins is of paramount importance for skeletal muscle hypertrophy, there are many other nutritional supplements that can help and support the physiological response of skeletal muscle to resistance training in terms of muscle hypertrophy. A healthy muscle environment and a correct whole muscle metabolism response to the stress of training is a prerequisite for the increase in muscle protein synthesis and, therefore, muscle hypertrophy. In this review, we discuss the role of different nutritional supplements such as carbohydrates, vitamins, minerals, creatine, omega-3, polyphenols, and probiotics as a support and complementary factors to the main supplement i.e., protein. The different mechanisms are discussed in the light of recent evidence.
54Gaba-producing lactobacilli boost cognitive reactivity to negative mood without improving cognitive performance: A human Double-Blind Placebo-Controlled Cross-Over study.PubMed
Melania Casertano, Matthijs Dekker, Vincenzo Valentino, et al.
Brain Behav Immun. 2024 Nov;122:256-265. doi: 10.1016/j.bbi.2024.08.029. Epub 2024 Aug 18.
BACKGROUND: Psychobiotic bacteria are probiotics able to influence stress-related behavior, sleep, and cognitive outcomes. Several in vitro and human studies were performed to assess their physiological potential, to find strains having psychotropic activity in humans, and to elucidate the metabolic pathways involved. In our previous in vitro study, we identified two strains Levilactobacillus brevis P30021 and Lactiplantibacillus plantarum P30025, able to produce GABA and acetylcholine, being promising candidates to provide an effect on mood and cognitive performance. AIM: To investigate the effects of probiotics in the alleviation on the cognitive performance of moderately stressed healthy adults. Secondary outcomes were related to mood improvement, production of GABA, glutamate, acetylcholine, and choline and modification of the microbiota composition. METHODS: A 12-week randomized, double-blind, placebo-controlled, cross-over study investigated the effects of a probiotic formulation (Levilactobacillus brevis P30021 and Lactiplantibacillus plantarum P30025) on psychological, memory, and cognition parameters in 44 (Probiotic = 44, Placebo = 43) adults with a mean age of 29 ± 5.7 years old by CogState Battery test. Subjects-inclusion criteria was a mild-moderate (18.7 ± 4.06) stress upon diagnosis using the DASS-42 questionnaire. RESULTS: Probiotic treatment had no effect on subjective stress measures. The probiotic formulation showed a significant beneficial effect on depressive symptoms by reducing cognitive reactivity to sad mood (p = 0.034). Rumination significantly improved after intake of the probiotic (p = 0.006), suggesting a potential benefit in reducing the negative cognitive effects associated with depression and improving overall mental health. When stratifying the treated subjects according to the response, we found an increase in the abundance of the probiotic genera in the gut microbiota of positive responders (p = 0.009 for Lactiplantibacillus and p = 0.004 for L.brevis). No relevant correlations were observed between the neurotransmitter concentration in the faecal sample, scores of LEIDS, DASS-42, and cognitive tests. CONCLUSION: We highlight the potential of this probiotic preparation to act as psycobiotics for the relief of negative mood feelings. The assessment of the psychotropic effects of dietary interventions in human participants has many challenges. Further interventional studies investigating the effect of these psychobiotic bacteria in populations with stressed-related disorders are required including longer period of intervention and larger sample size in order to verify the effects of the treatment on further stress-related indicators.
55Low energy availability increases immune cell formation of reactive oxygen species and impairs exercise performance in female endurance athletes.PubMed
Jan S Jeppesen, Hannah G Caldwell, Lone O Lossius, et al.
Redox Biol. 2024 Sep;75:103250. doi: 10.1016/j.redox.2024.103250. Epub 2024 Jun 19.
INTRODUCTION: The effects of low energy availability (LEA) on the immune system are poorly understood. This study examined the effects of 14 days of LEA on immune cell redox balance and inflammation at rest and in response to acute exercise, and exercise performance in female athletes. METHODS: Twelve female endurance athletes (age: 26.8 ± 3.4 yrs, maximum oxygen uptake (V˙O): 55.2 ± 5.1 mL × min × kg) were included in a randomized, single-blinded crossover study. They were allocated to begin with either 14 days of optimal energy availability diet (OEA, 52 ± 2 kcal × kg fat free mass (FFM) × day) or LEA diet (22 ± 2 kcal × kg FFM × day), followed by 3 days of refueling (OEA) with maintained training volume. Peripheral blood mononuclear cells (PBMCs) were isolated, and plasma obtained at rest before and after each dietary period. The PBMCs were used for analysis of mitochondrial respiration and HO emission and specific proteins. Exercise performance was assessed on cycle by a 20-min time trial and time to exhaustion at an intensity corresponding to ∼110 % V˙O). RESULTS: LEA was associated with a 94 % (P = 0.003) increase in PBMC NADPH oxidase 2 protein content, and a 22 % (P = 0.013) increase in systemic cortisol. LEA also caused an alteration of several inflammatory related proteins (P < 0.05). Acute exercise augmented HO emission in PBMCs (P < 0.001) following both OEA and LEA, but to a greater extent following LEA. LEA also reduced the mobilization of white blood cells with acute exercise. After LEA, performance was reduced in both exercise tests (P < 0.001), and the reduced time trial performance remained after the 3 days of refueling (P < 0.001). CONCLUSION: 14 days of LEA in female athletes increased cortisol levels and had a pronounced effect on the immune system, including increased capacity for ROS production, altered plasma inflammatory proteome and lowered exercise induced mobilization of leukocytes. Furthermore, LEA resulted in a sustained impairment in exercise performance.
56Male Endurance Athletes: Examination of Energy and Carbohydrate Availability and Hormone Responses.PubMed
Erin M Moore, Clemens Drenowatz, Brittany T Williams, et al.
Nutrients. 2024 Oct 31;16(21):3729. doi: 10.3390/nu16213729.
BACKGROUND: This study investigated the effects of decreased energy availability (EA) and carbohydrate availability (CA) on reproductive and metabolic hormones in male endurance-trained athletes. METHODS: Thirteen athletes (age: 26.08 ± 4.3 years; weight: 70.9 ± 6.5 kg; height: 179.9 ± 4.2 cm) participated in two training weeks with varying training volumes (low [LV] and high [HV]). The participants logged their diet and exercise for seven days and provided blood samples to measure hormone levels (Testosterone [T], insulin, leptin, cortisol, and interleukin-6 [IL-6]). RESULTS: Results showed that 46.2% (HV) and 38.5% (LV) of participants were at risk for low EA (≤25 kcal/kg FFM·d-1), while 53.8% (HV) and 69.2% (LV) had low CA (<6 g/kg). Strong positive correlations were found between leptin and body fat percentage (DXABFP) in both weeks (HV: r(11) = 0.88, < 0.001; LV: r(11) = 0.93, < 0.001). Moderate correlations were observed between T and DXABFP (r(11) = 0.56, = 0.05) and negative correlations between leptin and fat intake (r(11) = -0.60, = 0.03). Regression analyses indicated significant relationships between DXABFP and T (F(1,11) = 4.91, = 0.049), leptin (HV: F(1,11) = 40.56, < 0.001; LV: F(1,11) = 74.67, < 0.001), and cortisol (F(1,11) = 6.69, = 0.025). CONCLUSIONS: These findings suggest that monitoring body composition and macronutrients can be clinically useful for male athletes, especially those without access to blood testing. Ultimately, a greater understanding of health and performance outcomes for male athletes is needed.
57The interrelationship between sleep, diet, and glucose metabolism.PubMed
Marie-Pierre St-Onge, Anna Cherta-Murillo, Christian Darimont, et al.
Sleep Med Rev. 2023 Jun;69:101788. doi: 10.1016/j.smrv.2023.101788. Epub 2023 Apr 28.
Obesity and type 2 diabetes (T2D) are increasingly common worldwide. While these disorders have increased in prevalence over the past several decades, there has been a concomitant reduction in sleep duration. Short sleep duration has been associated with higher rates of obesity and T2D, and the causality of these associations and their directionality, continue to necessitate evaluation. In this review we consider the evidence that sleep is an intrinsic factor in the development of obesity and chronic metabolic disorders, such as insulin resistance and T2D, while evaluating a potential bi-directional association. We consider the evidence that diet and meal composition, which are known to impact glycemic control, may have both chronic and acute impact upon sleep. Moreover, we consider that postprandial nocturnal metabolism and peripheral glycemia may affect sleep quality. We propose putative mechanisms whereby acute effects of nighttime glucose excursions may lead to increased sleep fragmentation. We conclude that dietary manipulations, particularly with respect to carbohydrate quality, may confer sleep benefits. Future research may seek to evaluate the effectiveness of synergistic nutrient strategies to promote sleep quality, with particular attention to carbohydrate quality, quantity, and availability as well as carbohydrate to protein ratio.
58Regulation of Postabsorptive and Postprandial Glucose Metabolism by Insulin-Dependent and Insulin-Independent Mechanisms: An Integrative Approach.PubMed
George D Dimitriadis, Eirini Maratou, Aikaterini Kountouri, et al.
Nutrients. 2021 Jan 6;13(1):159. doi: 10.3390/nu13010159.
Glucose levels in blood must be constantly maintained within a tight physiological range to sustain anabolism. Insulin regulates glucose homeostasis via its effects on glucose production from the liver and kidneys and glucose disposal in peripheral tissues (mainly skeletal muscle). Blood levels of glucose are regulated simultaneously by insulin-mediated rates of glucose production from the liver (and kidneys) and removal from muscle; adipose tissue is a key partner in this scenario, providing nonesterified fatty acids (NEFA) as an alternative fuel for skeletal muscle and liver when blood glucose levels are depleted. During sleep at night, the gradual development of insulin resistance, due to growth hormone and cortisol surges, ensures that blood glucose levels will be maintained within normal levels by: (a) switching from glucose to NEFA oxidation in muscle; (b) modulating glucose production from the liver/kidneys. After meals, several mechanisms (sequence/composition of meals, gastric emptying/intestinal glucose absorption, gastrointestinal hormones, hyperglycemia mass action effects, insulin/glucagon secretion/action, de novo lipogenesis and glucose disposal) operate in concert for optimal regulation of postprandial glucose fluctuations. The contribution of the liver in postprandial glucose homeostasis is critical. The liver is preferentially used to dispose over 50% of the ingested glucose and restrict the acute increases of glucose and insulin in the bloodstream after meals, thus protecting the circulation and tissues from the adverse effects of marked hyperglycemia and hyperinsulinemia.
59Impact of fat, protein, and glycemic index on postprandial glucose control in type 1 diabetes: implications for intensive diabetes management in the continuous glucose monitoring era.PubMed
Kirstine J Bell, Carmel E Smart, Garry M Steil, et al.
Diabetes Care. 2015 Jun;38(6):1008-15. doi: 10.2337/dc15-0100.
BACKGROUND: Continuous glucose monitoring highlights the complexity of postprandial glucose patterns present in type 1 diabetes and points to the limitations of current approaches to mealtime insulin dosing based primarily on carbohydrate counting. METHODS: A systematic review of all relevant biomedical databases, including MEDLINE, Embase, CINAHL, and the Cochrane Central Register of Controlled Trials, was conducted to identify research on the effects of dietary fat, protein, and glycemic index (GI) on acute postprandial glucose control in type 1 diabetes and prandial insulin dosing strategies for these dietary factors. RESULTS: All studies examining the effect of fat (n = 7), protein (n = 7), and GI (n = 7) indicated that these dietary factors modify postprandial glycemia. Late postprandial hyperglycemia was the predominant effect of dietary fat; however, in some studies, glucose concentrations were reduced in the first 2-3 h, possibly due to delayed gastric emptying. Ten studies examining insulin bolus dose and delivery patterns required for high-fat and/or high-protein meals were identified. Because of methodological differences and limitations in experimental design, study findings were inconsistent regarding optimal bolus delivery pattern; however, the studies indicated that high-fat/protein meals require more insulin than lower-fat/protein meals with identical carbohydrate content. CONCLUSIONS: These studies have important implications for clinical practice and patient education and point to the need for research focused on the development of new insulin dosing algorithms based on meal composition rather than on carbohydrate content alone.
60Macronutrient Intake and Insulin Resistance in 5665 Randomly Selected, Non-Diabetic U.S. Adults.PubMed
Larry A Tucker
Nutrients. 2022 Feb 22;14(5):918. doi: 10.3390/nu14050918.
The main goal of this investigation was to evaluate the relationships between several macronutrients and insulin resistance in 5665 non-diabetic U.S. adults. A secondary objective was to determine the extent to which the associations were influenced by multiple potential confounding variables. A cross-sectional design and 8 years of data from the 2011-2018 National Health and Nutrition Examination Survey (NHANES) were used to answer the research questions. Ten macronutrients were evaluated: total carbohydrate, starch, simple carbohydrate, dietary fiber, total protein, total fat, saturated, polyunsaturated, monounsaturated, and total unsaturated fat. The homeostatic model assessment (HOMA), based on fasting glucose and fasting insulin levels, was used to index insulin resistance. Age, sex, race, year of assessment, physical activity, cigarette smoking, alcohol use, and waist circumference were used as covariates. The relationships between total carbohydrate intake (F = 6.7, = 0.0121), simple carbohydrate (F = 4.7, = 0.0344) and HOMA-IR were linear and direct. The associations between fiber intake (F = 9.1, = 0.0037), total protein (F = 4.4, = 0.0393), total fat (F = 5.5, = 0.0225), monounsaturated fat (F = 5.5, = 0.0224), and total unsaturated fat (F = 6.5, = 0.0132) were linear and inversely related to HOMA-IR, with 62 degrees of freedom. Starch, polyunsaturated fat, and saturated fat intakes were not related to HOMA-IR. In conclusion, in this nationally representative sample, several macronutrients were significant predictors of insulin resistance in U.S. adults.
61Insulin in Type 1 and Type 2 Diabetes-Should the Dose of Insulin Before a Meal be Based on Glycemia or Meal Content?PubMed
Janusz Krzymien, Piotr Ladyzynski
Nutrients. 2019 Mar 13;11(3):607. doi: 10.3390/nu11030607.
The aim of this review was to investigate existing guidelines and scientific evidence on determining insulin dosage in people with type 1 and type 2 diabetes, and in particular to check whether the prandial insulin dose should be calculated based on glycemia or the meal composition, including the carbohydrates, protein and fat content in a meal. By exploring the effect of the meal composition on postprandial glycemia we demonstrated that several factors may influence the increase in glycemia after the meal, which creates significant practical difficulties in determining the appropriate prandial insulin dose. Then we reviewed effects of the existing insulin therapy regimens on glycemic control. We demonstrated that in most existing algorithms aimed at calculating prandial insulin doses in type 1 diabetes only carbohydrates are counted, whereas in type 2 diabetes the meal content is often not taken into consideration. We conclude that prandial insulin doses in treatment of people with diabetes should take into account the pre-meal glycemia as well as the size and composition of meals. However, there are still open questions regarding the optimal way to adjust a prandial insulin dose to a meal and the possible benefits for people with type 1 and type 2 diabetes if particular parameters of the meal are taken into account while calculating the prandial insulin dose. The answers to these questions may vary depending on the type of diabetes.
62A Nutritional Approach to Optimizing Pump Therapy in Type 1 Diabetes Mellitus.PubMed
Evdoxia Gitsi, Sarantis Livadas, Nicholas Angelopoulos, et al.
Nutrients. 2023 Nov 23;15(23):4897. doi: 10.3390/nu15234897.
Achieving optimal glucose control in individuals with type 1 diabetes (T1DM) continues to pose a significant challenge. While continuous insulin infusion systems have shown promise as an alternative to conventional insulin therapy, there remains a crucial need for greater awareness regarding the necessary adaptations for various special circumstances. Nutritional choices play an essential role in the efficacy of diabetes management and overall health status for patients with T1DM. Factors such as effective carbohydrate counting, assessment of the macronutrient composition of meals, and comprehending the concept of the glycemic index of foods are paramount in making informed pre-meal adjustments when utilizing insulin pumps. Furthermore, the ability to handle such situations as physical exercise, illness, pregnancy, and lactation by making appropriate adjustments in nutrition and pump settings should be cultivated within the patient-practitioner relationship. This review aims to provide healthcare practitioners with practical guidance on optimizing care for individuals living with T1DM. It includes recommendations on carbohydrate counting, managing mixed meals and the glycemic index, addressing exercise-related challenges, coping with illness, and managing nutritional needs during pregnancy and lactation. Additionally, considerations relating to closed-loop systems with regard to nutrition are addressed. By implementing these strategies, healthcare providers can better equip themselves to support individuals with T1DM in achieving improved diabetes management and enhanced quality of life.
63Insulin pump dosing strategies for meals varying in fat, protein or glycaemic index or grazing-style meals in type 1 diabetes: A systematic review.PubMed
Mariam Metwally, Tin Oi Cheung, Roslyn Smith, et al.
Diabetes Res Clin Pract. 2021 Feb;172:108516. doi: 10.1016/j.diabres.2020.108516. Epub 2020 Oct 20.
BACKGROUND: Nutritional composition and food patterns influence postprandial glycaemia in type 1 diabetes (T1D). For optimal glycaemic control, insulin dose and delivery pattern must be matched accordingly. This systematic review aimed to compare insulin dosing strategies for meals varying in fat, protein and glycaemic index (GI), and prolonged meals in T1D. METHODS: Studies in adults and/or children with T1D on insulin pump therapy comparing the glycaemic effects of different insulin pump bolus types for these meal types were identified from biomedical databases (MEDLINE, PREMEDLINE, Embase, CINAHL and Cochrane Central Register of Controlled Trials; March 1995-April 2020) and systematically reviewed. RESULTS: All eleven publications investigating high-fat meals (234 participants) and all seven studies investigating high-protein meals (129 participants) showed a dual-wave bolus was superior. Additional insulin further improved postprandial glycaemia, although increasing risk of hypoglycaemia in 5 of 14 studies. One study investigating GI found a dual-wave bolus reduced postprandial glycaemia and risk of hypoglycaemia. No studies were identified for grazing/degustation-style meals. Due to heterogeneity, meta-analysis was not possible. CONCLUSION: Dual-wave boluses improve postprandial glycaemia in high-fat, high-protein and low-GI meals. Further research is needed to identify optimal bolus delivery split, duration and optimal total dose adjustment.
64Association between moderate consumption of ultra-processed foods and elevated hair cortisol levels: A cross-sectional analysis from the ELSA-Brasil cohort.PubMed
Karine Lino Rodrigues, Alessandra da Silva, Evelyn Nunes Goulart da Silva Pereira, et al.
J Affect Disord. 2026 Apr 1;398:121061. doi: 10.1016/j.jad.2025.121061. Epub 2025 Dec 29.
BACKGROUND: Ultra-processed foods (UPFs) are associated with metabolic disorders, mental health and stress-related behaviors. Chronic stress, marked by sustained cortisol elevation, may influence UPF intake. Hair cortisol is a reliable biomarker of long-term stress and enables a deeper understanding of this bidirectional association. OBJECTIVE: This study aimed to investigate the association between hair cortisol, a biomarker of chronic stress, and UPF consumption in the ELSA-Brasil cohort. METHODS: A cross-sectional analysis was performed on 2525 participants from the ELSA-Brasil cohort. Hair cortisol levels were categorized as low, normal, and high, and UPF consumption was expressed as the percentage of the total energy intake divided into tertiles. Multinomial logistic regression was performed to examine the association between cortisol levels and UPF consumption after adjusting for sociodemographic and behavioral factors. RESULTS: Individuals with high hair cortisol levels were 61 % more likely to be in the second tertile of UPF consumption (13.78-21.60 % of total energy intake) compared with the lowest tertile, even after adjustment for confounders. No significant association was observed between high cortisol levels and the highest UPF consumption in any tertile. These findings suggest a non-linear association, in which moderate UPF consumption may provoke a stronger physiological stress response than excessive intake. CONCLUSION: Moderate UPF consumption is significantly associated with elevated hair cortisol levels, emphasizing the importance of dietary and behavioral interventions to mitigate chronic stress. Reducing UPF intake, promoting increased consumption of unprocessed or minimally processed foods, and stress management strategies can be essential in addressing stress-related health outcomes.
65Effects of smartphone use with and without blue light at night in healthy adults: A randomized, double-blind, cross-over, placebo-controlled comparison.PubMed
Jung-Yoon Heo, Kiwon Kim, Maurizio Fava, et al.
J Psychiatr Res. 2017 Apr;87:61-70. doi: 10.1016/j.jpsychires.2016.12.010. Epub 2016 Dec 12.
Smartphones deliver light to users through Light Emitting Diode (LED) displays. Blue light is the most potent wavelength for sleep and mood. This study investigated the immediate effects of smartphone blue light LED on humans at night. We investigated changes in serum melatonin levels, cortisol levels, body temperature, and psychiatric measures with a randomized, double-blind, cross-over, placebo-controlled design of two 3-day admissions. Each subject played smartphone games with either conventional LED or suppressed blue light from 7:30 to 10:00PM (150 min). Then, they were readmitted and conducted the same procedure with the other type of smartphone. Serum melatonin levels were measured in 60-min intervals before, during and after use of the smartphones. Serum cortisol levels and body temperature were monitored every 120 min. The Profile of Mood States (POMS), Epworth Sleepiness Scale (ESS), Fatigue Severity Scale (FSS), and auditory and visual Continuous Performance Tests (CPTs) were administered. Among the 22 participants who were each admitted twice, use of blue light smartphones was associated with significantly decreased sleepiness (Cohen's d = 0.49, Z = 43.50, p = 0.04) and confusion-bewilderment (Cohen's d = 0.53, Z = 39.00, p = 0.02), and increased commission error (Cohen's d = -0.59, t = -2.64, p = 0.02). Also, users of blue light smartphones experienced a longer time to reach dim light melatonin onset 50% (2.94 vs. 2.70 h) and had increases in body temperature, serum melatonin levels, and cortisol levels, although these changes were not statistically significant. Use of blue light LED smartphones at night may negatively influence sleep and commission errors, while it may not be enough to lead to significant changes in serum melatonin and cortisol levels.
66Circadian Adaptation of Melatonin and Cortisol in Police Officers Working Rotating Shifts.PubMed
Anastasi Kosmadopoulos, Philippe Boudreau, Laura Kervezee, et al.
J Biol Rhythms. 2024 Feb;39(1):49-67. doi: 10.1177/07487304231196280. Epub 2023 Sep 26.
Misalignment of behavior and circadian rhythms due to night work can impair sleep and waking function. While both simulated and field-based studies suggest that circadian adaptation to a nocturnal schedule is slow, the rates of adaptation in real-world shift-work conditions are still largely unknown. The aim of this study was to evaluate the extent of adaptation of 24-h rhythms with 6-sulfatoxymelatonin (aMT6s) and cortisol in police officers working rotating shifts, with a special attention to night shifts. A total of 76 police officers (20 women; aged 32 ± 5.4 years, mean ± SD) from the province of Quebec, Canada, participated in a field study during their 28- or 35-day work cycle. Urine samples were collected for ~32 h before a series of day, evening, and night shifts to assess circadian phase. Before day, evening, and night shifts, 60%-89% of officers were adapted to a day schedule based on aMT6 rhythms, and 71%-78% were adapted based on cortisol rhythms. To further quantify the rate of circadian adaptation to night shifts, initial and final phases were determined in a subset of 37 officers with suitable rhythms for both hormones before and after 3-8 consecutive shifts (median = 7). Data were analyzed with circular and linear mixed-effects models. After night shifts, 30% and 24% of officers were adapted to a night-oriented schedule for aMT6s and cortisol, respectively. Significantly larger phase-delay shifts (aMT6s: -7.3 ± 0.9 h; cortisol: -6.3 ± 0.8 h) were observed in police officers who adapted to night shifts than in non-adapted officers (aMT6s: 0.8 ± 0.9 h; cortisol: 0.2 ± 1.1 h). Consistent with prior research, our results from both urinary aMT6s and cortisol midpoints indicate that a large proportion of police officers remained in a state of circadian misalignment following a series of night shifts in dim-light working environments.
67Diurnal variations of hormonal secretion, alertness and cognition in extreme chronotypes under different lighting conditions.PubMed
L Maierova, A Borisuit, J-L Scartezzini, et al.
Sci Rep. 2016 Sep 20;6:33591. doi: 10.1038/srep33591.
Circadian rhythms in physiology and behavior are modulated by external factors such as light or temperature. We studied whether self-selected office lighting during the habitual waking period had a different impact on alertness, cognitive performance and hormonal secretion in extreme morning and evening chronotypes (N = 32), whose preferred bed- and wake-up times differed by several hours. The self-selected lighting condition was compared with constant bright light and a control condition in dim light. Saliva samples for hormonal analyses, subjective ratings of alertness, wellbeing, visual comfort and cognitive performance were regularly collected. Between the self-selected and the bright, but not the dim lighting condition, the onset of melatonin secretion in the evening (as marker for circadian phase) was significantly different for both chronotypes. Morning chronotypes reported a faster increase in sleepiness during the day than evening chronotypes, which was associated with higher cortisol secretion. Wellbeing, mood and performance in more difficult cognitive tasks were better in bright and self-selected lighting than in dim light for both chronotypes, whereas visual comfort was best in the self-selected lighting. To conclude, self-selection of lighting at work might positively influence biological and cognitive functions, and allow for inter-individual differences.
68Characterizing Sleep in Adolescents and Adults with Autism Spectrum Disorders.PubMed
S E Goldman, M L Alder, H J Burgess, et al.
J Autism Dev Disord. 2017 Jun;47(6):1682-1695. doi: 10.1007/s10803-017-3089-1.
We studied 28 adolescents/young adults with autism spectrum disorders (ASD) and 13 age/sex matched individuals of typical development (TD). Structured sleep histories, validated questionnaires, actigraphy (4 weeks), and salivary cortisol and melatonin (4 days each) were collected. Compared to those with TD, adolescents/young adults with ASD had longer sleep latencies and more difficulty going to bed and falling asleep. Morning cortisol, evening cortisol, and the morning-evening difference in cortisol did not differ by diagnosis (ASD vs. TD). Dim light melatonin onsets (DLMOs) averaged across participants were not different for the ASD and TD participants. Average participant scores indicated aspects of poor sleep hygiene in both groups. Insomnia in ASD is multifactorial and not solely related to physiological factors.
69Dysregulated 24 h melatonin secretion associated with intrinsically photosensitive retinal ganglion cell function in diabetic retinopathy: a cross-sectional study.PubMed
Sirimon Reutrakul, Jason C Park, J Jason McAnany, et al.
Diabetologia. 2024 Jun;67(6):1114-1121. doi: 10.1007/s00125-024-06118-3. Epub 2024 Feb 27.
AIMS/HYPOTHESIS: The aim of this study was to explore whether diabetic retinopathy is associated with alterations of the circadian system, and to examine the role of reduced intrinsically photosensitive retinal ganglion cell (ipRGC) function. METHODS: Participants with type 2 diabetes, with diabetic retinopathy (n=14) and without diabetic retinopathy (n=9) underwent 24 h blood sampling for melatonin and cortisol under controlled laboratory conditions. ipRGC function was inferred from the post-illumination pupil response (PIPR). Habitual sleep duration, efficiency and variability were assessed by actigraphy. RESULTS: Participants with diabetic retinopathy compared to participants without diabetic retinopathy had smaller PIPR (p=0.007), lower 24 h serum melatonin output (p=0.042) and greater day-to-day sleep variability (p=0.012). By contrast, 24 h cortisol profiles, sleep duration and efficiency were similar in both groups. Six individuals with diabetic retinopathy had no detectable dim-light melatonin onset. PIPR correlated with 24 h mean melatonin levels (r=0.555, p=0.007). CONCLUSIONS/INTERPRETATION: ipRCG dysfunction in diabetic retinopathy is associated with disruptions of the 24 h melatonin rhythm, suggesting circadian dysregulation in diabetic retinopathy.
70Resetting the late timing of 'night owls' has a positive impact on mental health and performance.PubMed
Elise R Facer-Childs, Benita Middleton, Debra J Skene, et al.
Sleep Med. 2019 Aug;60:236-247. doi: 10.1016/j.sleep.2019.05.001. Epub 2019 May 10.
BACKGROUND: There is conflict between living according to our endogenous biological rhythms and our external environment, with disruptions resulting in negative consequences to health and performance. This is often documented in shift work and jet lag, but 'societal norms' (eg, typical working hours) can create profound issues for 'night owls', people whose internal biological timing predisposes them to follow an unusually late sleep-wake cycle. Night owls have also been associated with health issues, mood disturbances, poorer performance and increased mortality rates. METHODS: This study used a randomized control trial design aimed to shift the late timing of night owls to an earlier time (phase advance), using non-pharmacological, practical interventions in a real-world setting. These interventions targeted light exposure (through earlier wake up/sleep times), fixed meals times, caffeine intake and exercise. RESULTS: Overall, participants demonstrated a significant advance of ∼2 h in sleep/wake timings as measured by actigraphy and circadian phase markers (dim light melatonin onset and peak time of the cortisol awakening response), whilst having no adverse effect on sleep duration. Notably, the phase advance was accompanied by significant improvements to self-reported depression and stress, as well as improved cognitive (reaction time) and physical (grip strength) performance measures during the typical 'suboptimal' morning hours. CONCLUSIONS: Our findings propose a novel strategy for shifting clock timing towards a pattern that is more aligned to societal demands that could significantly improve elements of performance, mental health and sleep timing in the real world.
71How environmental conditions affect sleep? An investigation in domestic dogs (Canis lupus familiaris).PubMed
Ivana Gabriela Schork, Isabele Aparecida Manzo, Marcos Roberto Beiral De Oliveira, et al.
Behav Processes. 2022 Jun;199:104662. doi: 10.1016/j.beproc.2022.104662. Epub 2022 May 27.
Studies with humans and some other animal species have shown that sleep is compromised when the presence of external factors such as light, sound, and temperature surpass normal levels. This study investigated the effects of these environmental conditions on 13 kennelled laboratory dogs, assessing whether each variable interfered with their sleep behaviour and/or increased stress responses, which could further compromise sleep quality. The behaviour of dogs was video recorded for eight months. Diurnal and nocturnal behaviour were recorded, along with naturally occurring levels of temperature, light and sound in the dogs' kennel environment. Faecal cortisol metabolites (FCM), from samples collected every morning, were used to monitor the dogs' adrenocortical activity. GLMM models and non-parametric tests were conducted to evaluate the relationship between sleeping patterns, environmental variables, and stress on the studied dogs. Nocturnal sleep decreased in response to increases in temperature and in day light duration. No effects of sound and FCM levels on dogs' sleep were observed. However, diurnal sleep was affected by sound and FCM levels, decreasing when both factors increased. Additionally, noisier days increased stress responses, especially in male dogs. Increased FCM levels were associated with changes in the diurnal behaviour of dogs; for example, decreased activity. The decrease in daily activities and increased physiological stress responses could be associated with maladaptation to the environment, which could indicate poor welfare. Our study suggests that mitigating the impact of environmental conditions in the kennels could improve sleep quality and the overall quality of life of the dogs.
72Yoga, mindfulness-based stress reduction and stress-related physiological measures: A meta-analysis.PubMed
Michaela C Pascoe, David R Thompson, Chantal F Ski
Psychoneuroendocrinology. 2017 Dec;86:152-168. doi: 10.1016/j.psyneuen.2017.08.008. Epub 2017 Aug 30.
BACKGROUND AND OBJECTIVES: Practices that include yoga asanas and mindfulness-based stress reduction for the management of stress are increasingly popular; however, the neurobiological effects of these practices on stress reactivity are not well understood. Many studies investigating the effects of such practices fail to include an active control group. Given the frequency with which people are selecting such interventions as a form of self-management, it is important to determine their effectiveness. Thus, this review investigates the effects of practices that include yoga asanas, with and without mindfulness-based stress reduction, compared to an active control, on physiological markers of stress. MATERIALS AND METHODS: A systematic review and meta-analysis of randomised controlled trials published in English compared practices that included yoga asanas, with and without mindfulness-based stress reduction, to an active control, on stress-related physiological measures. The review focused on studies that measured physiological parameters such as blood pressure, heart rate, cortisol and peripheral cytokine expression. MEDLINE, AMED, CINAHL, PsycINFO, SocINDEX, PubMed, and Scopus were searched in May 2016 and updated in December 2016. Randomised controlled trials were included if they assessed at least one of the following outcomes: heart rate, blood pressure, heart rate variability, mean arterial pressure, C-reactive protein, interleukins or cortisol. Risk of bias assessments included sequence generation, allocation concealment, blinding of assessors, incomplete outcome data, selective outcome reporting and other sources of bias. Meta-analysis was undertaken using Comprehensive Meta-Analysis Software Version 3. Sensitivity analyses were performed using 'one-study-removed' analysis. Subgroup analysis was conducted for different yoga and control group types, including mindfulness-based stress reduction versus non-mindfulness-based stress reduction based interventions, different populations, length of intervention, and method of data analysis. A random-effects model was used in all analyses. RESULTS: Forty two studies were included in the meta-analysis. Interventions that included yoga asanas were associated with reduced evening cortisol, waking cortisol, ambulatory systolic blood pressure, resting heart rate, high frequency heart rate variability, fasting blood glucose, cholesterol and low density lipoprotein, compared to active control. However, the reported interventions were heterogeneous. CONCLUSIONS: Practices that include yoga asanas appear to be associated with improved regulation of the sympathetic nervous system and hypothalamic-pituitary-adrenal system in various populations.
73Meditation programs for psychological stress and well-being: a systematic review and meta-analysis.PubMed
Madhav Goyal, Sonal Singh, Erica M S Sibinga, et al.
JAMA Intern Med. 2014 Mar;174(3):357-68. doi: 10.1001/jamainternmed.2013.13018.
IMPORTANCE: Many people meditate to reduce psychological stress and stress-related health problems. To counsel people appropriately, clinicians need to know what the evidence says about the health benefits of meditation. OBJECTIVE: To determine the efficacy of meditation programs in improving stress-related outcomes (anxiety, depression, stress/distress, positive mood, mental health-related quality of life, attention, substance use, eating habits, sleep, pain, and weight) in diverse adult clinical populations. EVIDENCE REVIEW: We identified randomized clinical trials with active controls for placebo effects through November 2012 from MEDLINE, PsycINFO, EMBASE, PsycArticles, Scopus, CINAHL, AMED, the Cochrane Library, and hand searches. Two independent reviewers screened citations and extracted data. We graded the strength of evidence using 4 domains (risk of bias, precision, directness, and consistency) and determined the magnitude and direction of effect by calculating the relative difference between groups in change from baseline. When possible, we conducted meta-analyses using standardized mean differences to obtain aggregate estimates of effect size with 95% confidence intervals. FINDINGS: After reviewing 18 753 citations, we included 47 trials with 3515 participants. Mindfulness meditation programs had moderate evidence of improved anxiety (effect size, 0.38 [95% CI, 0.12-0.64] at 8 weeks and 0.22 [0.02-0.43] at 3-6 months), depression (0.30 [0.00-0.59] at 8 weeks and 0.23 [0.05-0.42] at 3-6 months), and pain (0.33 [0.03- 0.62]) and low evidence of improved stress/distress and mental health-related quality of life. We found low evidence of no effect or insufficient evidence of any effect of meditation programs on positive mood, attention, substance use, eating habits, sleep, and weight. We found no evidence that meditation programs were better than any active treatment (ie, drugs, exercise, and other behavioral therapies). CONCLUSIONS AND RELEVANCE: Clinicians should be aware that meditation programs can result in small to moderate reductions of multiple negative dimensions of psychological stress. Thus, clinicians should be prepared to talk with their patients about the role that a meditation program could have in addressing psychological stress. Stronger study designs are needed to determine the effects of meditation programs in improving the positive dimensions of mental health and stress-related behavior.
74Depression and Anxiety Disorders: Benefits of Exercise, Yoga, and Meditation.PubMed
Sy Atezaz Saeed, Karlene Cunningham, Richard M Bloch
Am Fam Physician. 2019 May 15;99(10):620-627.
Many people with depression or anxiety turn to nonpharmacologic and nonconventional interventions, including exercise, yoga, meditation, tai chi, or qi gong. Meta-analyses and systematic reviews have shown that these interventions can improve symptoms of depression and anxiety disorders. As an adjunctive treatment, exercise seems most helpful for treatment-resistant depression, unipolar depression, and posttraumatic stress disorder. Yoga as monotherapy or adjunctive therapy shows positive effects, particularly for depression. As an adjunctive therapy, it facilitates treatment of anxiety disorders, particularly panic disorder. Tai chi and qi gong may be helpful as adjunctive therapies for depression, but effects are inconsistent. As monotherapy or an adjunctive therapy, mindfulness-based meditation has positive effects on depression, and its effects can last for six months or more. Although positive findings are less common in people with anxiety disorders, the evidence supports adjunctive use. There are no apparent negative effects of mindfulness-based interventions, and their general health benefits justify their use as adjunctive therapy for patients with depression and anxiety disorders.
75The Effect of Deep Breathing Exercise and 4-7-8 Breathing Techniques Applied to Patients After Bariatric Surgery on Anxiety and Quality of Life.PubMed
Gülfidan Kurt Aktaş, Vesile Eskici İlgin
Obes Surg. 2023 Mar;33(3):920-929. doi: 10.1007/s11695-022-06405-1. Epub 2022 Dec 8.
BACKGROUND: This study aims to determine the effects of the deep breathing exercise and the 4-7-8 breathing technique applied to patients after bariatric surgery on their anxiety and quality of life. METHODS: The research was carried out using the pre-test post-test randomized controlled experimental research design with a control group. A total of 90 patients (30 patients in the deep breathing group, 30 patients in the 4-7-8 breathing group, and 30 patients in the control group) who met the research inclusion criteria were included in the study. While routine care was applied to the control group, 1 group was given deep breathing training, and the other group was given 4-7-8 breathing training. Personal Information Form, the Obesity-Specific Quality of Life Questionnaire, Status, and the State-Trait Anxiety Inventory were used for data collection. RESULTS: There was no significant difference between the groups in terms of descriptive characteristics (p > 0.05). It was found that the post-test State Anxiety levels of the 4-7-8 breathing group were lower than the mean scores of the deep breathing group and the control group, and the difference was statistically significant (p < 0.05). It was found that the quality of life scores of the patients in the deep breathing group increased significantly in the post-test compared to the pre-test. CONCLUSION: The 4-7-8 breathing technique was found to be beneficial in reducing the anxiety level of patients in clinical practice after bariatric surgery. It was found that deep breathing exercise was also effective in improving the quality of life. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT05492929.
76The effect of breathing exercises on pain, sleep, and symptom management in patients undergoing hemodialysis: a randomized controlled trial.PubMed
Yasemin Özyer Güvener, Zeliha Koç
Sleep Breath. 2025 Apr 25;29(2):170. doi: 10.1007/s11325-025-03332-0.
PURPOSE: This study was conducted to determine the effect of breathing exercises on pain, sleep, and symptom management in patients undergoing hemodialysis. METHODS: The randomized controlled study was conducted with patients undergoing hemodialysis at a private dialysis center in the northern Black Sea region. Data were collected using the Descriptive Information Form, the Visual Analog Scale (VAS), the Richards-Campbell Sleep Questionnaire (RCSQ), the Dialysis Symptom Index (DSI), and the Vital Signs Form. According to the power analysis performed in the study, a total of 70 participants, 35 in each group, needed to be included in the study in order to conduct an independent t-test with a confidence level of 95%, a test power of 95%, and an effect size of d = 0.80. The study was conducted with a total of 69 patients divided into two groups: the experimental group (n = 35) and the control group (n = 34). Patients in the experimental group performed breathing exercises (Diaphragmatic breathing, Agni Sār, Nadi Shodhana, and the 4-7-8 breathing technique) on dialysis days for eight weeks. During this period, patients in the control group continued to receive routine nursing care in the hemodialysis unit. RESULTS: Following the application, the average pain intensity in the control group (4.06 ± 3.1) was found to be statistically significantly higher than the average in the experimental group (0.4 ± 1.19) (p < 0.001). The average sleep score in the control group (48.56 ± 22.35) was found to be statistically significantly lower than the average in the experimental group (80.21 ± 16.46) (p < 0.001). The average DSI in the control group (92 ± 22.05) was found to be statistically significantly higher than the average in the experimental group (41.37 ± 7.15) (p < 0.001). CONCLUSION: Breathing exercises in patients undergoing hemodialysis were found to reduce pain, improve sleep quality, and have a positive impact on symptom management. In light of this, it is recommended that nurses include breathing techniques as part of the care provided to hemodialysis patients. Using complementary methods such as breathing therapy supports the physical, psychological, psychosocial, and holistic care of patients, thus increasing patient satisfaction and quality of life. Training health professionals in breathing therapy will ensure a broader use of this complementary method in a larger patient population.
774-7-8 Breathing Techniques Make It Possible to Reduce Pain Associated With Total Knee Arthroplasty: A New Technique in Respiratory Exercises.PubMed
Zehra Eskimez, Alev Keskin, Ece Kurt, et al.
J Perianesth Nurs. 2025 Jul 30. doi: 10.1016/j.jopan.2025.04.009.
PURPOSE: Orthopedic and traumatology surgeries performed to repair or reconstruct muscles, bones, and soft tissues are known to cause severe postoperative pain, and various interventions can be used for effective pain management. This study aims to evaluate the effect of the 4-7-8 breathing technique on postoperative pain intensity in patients undergoing total knee arthroplasty. DESIGN: The study used a quasi-experimental method focusing on a single-group pre-post test design. METHODS: The research study was conducted between April 2022 and May 2023 at a university hospital in southern Turkey. The 4-7-8 breathing technique was taught to patients by the researcher one day before surgery and was applied postoperatively. Pain assessment was conducted using the Numerical Rating Scale at three time points: before the breathing technique was applied, immediately after, and 30 minutes later. Data were analyzed using the Mann-Whitney U, Kruskal-Wallis H, and Friedman tests. FINDINGS: The study participants had a mean age of 67.24 ± 8.30 years; the majority (83.6%) were women. The average pain score was 7.25 ± 1.28 before the postsurgical breathing exercise, decreasing to 6.27 ± 1.4 immediately after surgery and further to 3.84 ± 2.01 after 30 minutes. The differences in pain intensity across these time points were statistically significant (ꭓ² = 90.921; P < .001). CONCLUSIONS: The 4-7-8 breathing technique has been shown to effectively reduce pain intensity in patients undergoing total knee arthroplasty. As a simple, cost-effective, and noninvasive method, it can be easily taught by nurses and incorporated into postoperative care. Integrating this technique into pain management may improve patient recovery and overall well-being.
78Effects of sleep deprivation and 4-7-8 breathing control on heart rate variability, blood pressure, blood glucose, and endothelial function in healthy young adults.PubMed
Jaruwan Vierra, Orachorn Boonla, Piyapong Prasertsri
Physiol Rep. 2022 Jul;10(13):e15389. doi: 10.14814/phy2.15389.
This study investigated the effects of sleep deprivation on heart rate variability (HRV), blood pressure (BP), fasting blood glucose (FBG), and endothelial function as well as the immediate effects of 4-7-8 breathing control on HRV and BP. In total, 43 healthy participants aged 19-25 years were classified into two groups: Twenty two in the with sleep deprivation group and 21 in the without sleep deprivation (control) group. Resting heart rate (HR), BP, HRV, FBG, and endothelial function were examined. Subsequently, participants practiced 4-7-8 breathing control for six cycles/set for three sets interspersed between each set by 1-min normal breathing. Thereafter, the HR, BP, and HRV were immediately examined. The HRV, HR, and BP variables and FBG were not significantly different between the two groups. However, endothelial function was significantly lower in the sleep deprivation group than that in the control group (p < 0.05). In response to 4-7-8 breathing control, low- and very-low-frequency powers significantly decreased (p < 0.05), whereas high-frequency power significantly increased (p < 0.05) in the control group. Moreover, time domain, total power, and very-low-frequency power significantly decreased (p < 0.05) in the sleep deprivation group. Both groups had significantly decreased HR and systolic BP (p < 0.05). HRV, HR, and BP variables showed no significant differences between the groups. Healthy young adults with and without sleep deprivation may have similar HRV, BP, and FBG values. However, sleep deprivation may cause decreased endothelial function. Furthermore, 4-7-8 breathing control can help participants improve their HRV and BP, particularly in those without sleep deprivation.
79Effects of health education and progressive muscle relaxation on vasomotor symptoms and insomnia in perimenopausal women: A randomized controlled trial.PubMed
Sıdıka Pelit Aksu, Ayten Şentürk Erenel
Patient Educ Couns. 2022 Nov;105(11):3279-3286. doi: 10.1016/j.pec.2022.07.015. Epub 2022 Jul 28.
OBJECTIVES: This study aims to determine the effects of health education (HE) and progressive muscle relaxation (PMR), individually or combined, on vasomotor symptoms and insomnia in perimenopausal women. METHODS: This study is a single-center, pretest-posttest, randomized controlled trial with a factorial design. The research sample consists of 108 women who were randomly divided into three groups: HE + PMR group (n = 36), PMR group (n = 36) and control group (n = 36). 90 women completed the study. The data were collected in three steps by using instruments of Personal Information Form, Visual Analog Scale and a diary for vasomotor symptoms, Women's Health Initiative Insomnia Rating Scale. RESULTS: Hot flash and night sweats frequency and severity scores/24 h, the VAS scores for hot flashes and night sweats, and the WHIIRS scores significantly improved more in the intervention groups compared to the control group (p < 0,05). Compared to the group PMR, the group PMR + HE had a greater improvement with larger effect size in all measurements. CONCLUSIONS: PMR and HE counseling by nurses benefit perimenopausal women who suffer from insomnia and vasomotor symptoms. PRACTICE IMPLICATIONS: PMR combined with HE or PMR alone is effective in managing vasomotor symptoms and insomnia; therefore, they can easily be integrated into clinical practice.
80Effectiveness of Progressive Muscle Relaxation and Deep Breathing Exercise on Pain, Disability, and Sleep Among Patients With Chronic Tension-Type Headache: A Randomized Control Trial.PubMed
Lakshmanan Gopichandran, Achal Kumar Srivastsava, P Vanamail, et al.
Holist Nurs Pract. 2024;38(5):285-296. doi: 10.1097/HNP.0000000000000460. Epub 2024 Aug 16.
A randomized control trial was conducted to assess the effectiveness of progressive muscle relaxation and deep breathing exercises on pain, disability, and sleep quality among patients with chronic tension-type headache. Of the 169 randomly selected patients, 84 performed the intervention and reported less pain severity and disability and better sleep quality after 12 weeks.
81The effects of progressive muscle relaxation exercise applied to lung cancer patients receiving chemotherapy on dyspnea, pain and sleep quality: A randomized controlled trial.PubMed
Gülcan Bahcecioglu Turan, Zülfünaz Özer, Ayşegül Sariköse
Eur J Oncol Nurs. 2024 Jun;70:102580. doi: 10.1016/j.ejon.2024.102580. Epub 2024 Apr 1.
PURPOSE: The aim of the present study is the analysis of how progressive muscle relaxation exercise affects dyspnea, pain and sleep quality in patients with lung cancer receiving chemotherapy. METHODS: Seventy-four patients diagnosed with lung cancer were included in this randomized controlled study. A total of 16 sessions of progressive muscle relaxation exercises were applied to the patients in the intervention group for a duration of 30 min, 2 days a week for 8 weeks. Patient Information Form, Medical Research Council Dyspnea Scale (MRC dyspnea scale), Pitssburg Sleep Quality Index (PSQI), Visual Analog Scale- Pain (VAS-P) were used to collect data. RESULTS: Socio-demographic and disease characteristics were found to be similar in control and intervention groups. Final scores indicated significant differences between the experimental and control groups in all variables. The experimental group showed significantly more favorable results in dyspnea (p < 0.001), pain (p < 0.003) and sleep (p < 0.001) symptoms. When the effect size values (Cohen's d) of these findings were analyzed, PMR exercise was found to have a moderate effect on mean VAS-P scores (0.548) and a large effect on mean MRC dyspnea scale (1.073) and PSQI (0.970) scores. These results indicated significant differences in pre and post intervention mean scores. CONCLUSION: Progressive muscle relaxation exercise applied to lung cancer patients receiving chemotherapy was found to be effective in reducing dyspnea and pain severity and improving sleep quality. Clinical trial registration at ClinicalTrials.gov. NCT04978805.
82Management of chronic pain secondary to temporomandibular disorders: a systematic review and network meta-analysis of randomised trials.PubMed
Liang Yao, Behnam Sadeghirad, Meixuan Li, et al.
BMJ. 2023 Dec 15;383:e076226. doi: 10.1136/bmj-2023-076226.
OBJECTIVE: We explored the comparative effectiveness of available therapies for chronic pain associated with temporomandibular disorders (TMD). DESIGN: Systematic review and network meta-analysis of randomised clinical trials (RCTs). DATA SOURCES: MEDLINE, EMBASE, CINAHL, CENTRAL, and SCOPUS were searched to May 2021, and again in January 2023. STUDY SELECTION: Interventional RCTs that enrolled patients presenting with chronic pain associated with TMD. DATA EXTRACTION AND SYNTHESIS: Pairs of reviewers independently identified eligible studies, extracted data, and assessed risk of bias. We captured all reported patient-important outcomes, including pain relief, physical functioning, emotional functioning, role functioning, social functioning, sleep quality, and adverse events. We conducted frequentist network meta-analyses to summarise the evidence and used the GRADE approach to rate the certainty of evidence and categorise interventions from most to least beneficial. RESULTS: 233 trials proved eligible for review, of which 153-enrolling 8713 participants and exploring 59 interventions or combinations of interventions-were included in network meta-analyses. All subsequent effects refer to comparisons with placebo or sham procedures. Effects on pain for eight interventions were supported by high to moderate certainty evidence. The three therapies probably most effective for pain relief were cognitive behavioural therapy (CBT) augmented with biofeedback or relaxation therapy (risk difference (RD) for achieving the minimally important difference (MID) in pain relief of 1 cm on a 10 cm visual analogue scale: 36% (95% CI 33 to 39)), therapist-assisted jaw mobilisation (RD 36% (95% CI 31 to 40)), and manual trigger point therapy (RD 32% (29 to 34)). Five interventions were less effective, yet more effective than placebo, showing RDs ranging between 23% and 30%: CBT, supervised postural exercise, supervised jaw exercise and stretching, supervised jaw exercise and stretching with manual trigger point therapy, and usual care (such as home exercises, self stretching, reassurance).Moderate certainty evidence showed four interventions probably improved physical functioning: supervised jaw exercise and stretching (RD for achieving the MID of 5 points on the short form-36 physical component summary score: 43% (95% CI 33 to 51)), manipulation (RD 43% (25 to 56)), acupuncture (RD 42% (33 to 50)), and supervised jaw exercise and mobilisation (RD 36% (19 to 51)). The evidence for pain relief or physical functioning among other interventions, and all evidence for adverse events, was low or very low certainty. CONCLUSION: When restricted to moderate or high certainty evidence, interventions that promote coping and encourage movement and activity were found to be most effective for reducing chronic TMD pain. REGISTRATION: PROSPERO (CRD42021258567).
83'Natural' light treatment of seasonal affective disorder.PubMed
A Wirz-Justice, P Graw, K Kräuchi, et al.
J Affect Disord. 1996 Apr 12;37(2-3):109-20. doi: 10.1016/0165-0327(95)00081-x.
Patients with seasonal affective disorder (SAD) were treated for 1 week either with a daily 1-h morning walk outdoors (natural light) or low-dose artificial light (0.5 h@2800 lux). The latter treatment (given under double-blind conditions) can be considered mainly placebo and did not improve any of the depression self-ratings, whereas natural light exposure improved all self-ratings. According to the Hamilton depression score, 25% remitted after low-dose artificial light and 50% after the walk. Sleep duration or timing were not crucial for the therapeutic response. The morning walk phase-advanced the onset and/or offset of salivary melatonin secretion, but individual clinical improvement could not be correlated with specific phase-shifts. Morning cortisol was decreased. Low-dose artificial light did not modify melatonin or cortisol patterns. This is the first study to provide evidence for the use of outdoor light exposure as a potential alternative or adjuvant to conventional artificial light therapy in SAD.
84The Influence of Light Wavelength on Human HPA Axis Rhythms: A Systematic Review.PubMed
Isabella Robertson-Dixon, Melanie J Murphy, Sheila G Crewther, et al.
Life (Basel). 2023 Sep 26;13(10):1968. doi: 10.3390/life13101968.
Environmental light entrains many physiological and behavioural processes to the 24 h solar cycle. Such light-driven circadian rhythms are centrally controlled by the suprachiasmatic nucleus (SCN), which receives information from the short-wavelength-sensitive intrinsically photosensitive retinal ganglion cells. The SCN synchronizes local clocks throughout the body affecting sleep/wake routines and the secretion of neuroendocrine-linked hormones such as melatonin from the pineal gland and cortisol via the hypothalamic pituitary adrenal (HPA) axis. Although the effects of light parameters on melatonin have been recently reviewed, whether the experimental variation of the spectral power distribution and intensity of light can induce changes in cortisol rhythms remains unclear. Thus, this systematic review evaluated the effects of daytime exposure to lights of different spectral wavelength characteristics and luminance intensity on the cortisol levels in healthy individuals. A search of the PubMed, Web of Science, EMBASE, CINAHL, Medline, PsycINFO and Cochrane Library databases on 19 June 2023 identified 3418 articles, of which 12 studies (profiling 337 participants) met the inclusion and risk of bias criteria. An analysis of the literature indicated that exposure to bright lights of any colour during the late night or early morning can induce significant increases in cortisol secretion relative to time-matched dim light comparison conditions. Furthermore, exposure to bright lights with stronger short-wavelength (blue/green) components in the early morning typically induced greater increases in cortisol relative to lights with stronger long-wavelength (red) components. Thus, the circadian regulation of cortisol is sensitive to the wavelength composition of environmental lighting, in line with the more commonly studied melatonin. As such, wavelength characteristics should be optimized and reported in light intervention studies (particularly for the investigation of cortisol-associated disorders and HPA axis function), and exposure to short-wavelength light during sensitive periods should be carefully considered in constructed environments (e.g., bedroom and classroom lighting and device screens).
85Electric light, particularly at night, disrupts human circadian rhythmicity: is that a problem?PubMed
Richard G Stevens, Yong Zhu
Philos Trans R Soc Lond B Biol Sci. 2015 May 5;370(1667). doi: 10.1098/rstb.2014.0120.
Over the past 3 billion years, an endogenous circadian rhythmicity has developed in almost all life forms in which daily oscillations in physiology occur. This allows for anticipation of sunrise and sunset. This physiological rhythmicity is kept at precisely 24 h by the daily cycle of sunlight and dark. However, since the introduction of electric lighting, there has been inadequate light during the day inside buildings for a robust resetting of the human endogenous circadian rhythmicity, and too much light at night for a true dark to be detected; this results in circadian disruption and alters sleep/wake cycle, core body temperature, hormone regulation and release, and patterns of gene expression throughout the body. The question is the extent to which circadian disruption compromises human health, and can account for a portion of the modern pandemics of breast and prostate cancers, obesity, diabetes and depression. As societies modernize (i.e. electrify) these conditions increase in prevalence. There are a number of promising leads on putative mechanisms, and epidemiological findings supporting an aetiologic role for electric lighting in disease causation. These include melatonin suppression, circadian gene expression, and connection of circadian rhythmicity to metabolism in part affected by haem iron intake and distribution.
86Ancestral sleep.PubMed
Horacio O de la Iglesia, Claudia Moreno, Arne Lowden, et al.
Curr Biol. 2016 Apr 4;26(7):R271-2. doi: 10.1016/j.cub.2016.01.071.
While we do not yet understand all the functions of sleep, its critical role for normal physiology and behaviour is evident. Its amount and temporal pattern depend on species and condition. Humans sleep about a third of the day with the longest, consolidated episode during the night. The change in lifestyle from hunter-gatherers via agricultural communities to densely populated industrialized centres has certainly affected sleep, and a major concern in the medical community is the impact of insufficient sleep on health [1,2]. One of the causal mechanisms leading to insufficient sleep is altered exposure to the natural light-dark cycle. This includes the wide availability of electric light, attenuated exposure to daylight within buildings, and evening use of light-emitting devices, all of which decrease the strength of natural light-dark signals that entrain circadian systems [3].
87Nocturnal light pollution and underexposure to daytime sunlight: Complementary mechanisms of circadian disruption and related diseases.PubMed
Michael H Smolensky, Linda L Sackett-Lundeen, Francesco Portaluppi
Chronobiol Int. 2015;32(8):1029-48. doi: 10.3109/07420528.2015.1072002. Epub 2015 Sep 16.
Routine exposure to artificial light at night (ALAN) in work, home, and community settings is linked with increased risk of breast and prostate cancer (BC, PC) in normally sighted women and men, the hypothesized biological rhythm mechanisms being frequent nocturnal melatonin synthesis suppression, circadian time structure (CTS) desynchronization, and sleep/wake cycle disruption with sleep deprivation. ALAN-induced perturbation of the CTS melatonin synchronizer signal is communicated maternally at the very onset of life and after birth via breast or artificial formula feedings. Nighttime use of personal computers, mobile phones, electronic tablets, televisions, and the like--now epidemic in adolescents and adults and highly prevalent in pre-school and school-aged children--is a new source of ALAN. However, ALAN exposure occurs concomitantly with almost complete absence of daytime sunlight, whose blue-violet (446-484 nm λ) spectrum synchronizes the CTS and whose UV-B (290-315 nm λ) spectrum stimulates vitamin D synthesis. Under natural conditions and clear skies, day/night and annual cycles of UV-B irradiation drive corresponding periodicities in vitamin D synthesis and numerous bioprocesses regulated by active metabolites augment and strengthen the biological time structure. Vitamin D insufficiency and deficiency are widespread in children and adults in developed and developing countries as a consequence of inadequate sunlight exposure. Past epidemiologic studies have focused either on exposure to too little daytime UV-B or too much ALAN, respectively, on vitamin D deficiency/insufficiency or melatonin suppression in relation to risk of cancer and other, e.g., psychiatric, hypertensive, cardiac, and vascular, so-called, diseases of civilization. The observed elevated incidence of medical conditions the two are alleged to influence through many complementary bioprocesses of cells, tissues, and organs led us to examine effects of the totality of the artificial light environment in which humans reside today. Never have chronobiologic or epidemiologic investigations comprehensively researched the potentially deleterious consequences of the combination of suppressed vitamin D plus melatonin synthesis due to life in today's man-made artificial light environment, which in our opinion is long overdue.
88Ocular and systemic melatonin and the influence of light exposure.PubMed
Lisa A Ostrin
Clin Exp Optom. 2019 Mar;102(2):99-108. doi: 10.1111/cxo.12824. Epub 2018 Aug 3.
Melatonin is a neurohormone known to modulate a wide range of circadian functions, including sleep. The synthesis and release of melatonin from the pineal gland is heavily influenced by light stimulation of the retina, particularly through the intrinsically photosensitive retinal ganglion cells. Melatonin is also synthesised within the eye, although to a much lesser extent than in the pineal gland. Melatonin acts directly on ocular structures to mediate a variety of diurnal rhythms and physiological processes within the eye. The interactions between melatonin, the eye, and visual function have been the subject of a considerable body of recent research. This review is intended to provide a broad introduction for eye-care practitioners and researchers to the topic of melatonin and the eye. The first half of the review describes the anatomy and physiology of melatonin production: how visual inputs affect the pineal production of melatonin; how melatonin is involved in a variety of diurnal rhythms within the eye, including photoreceptor disc shedding, neuronal sensitivity, and intraocular pressure control; and melatonin production and physiological roles in retina, ciliary body, lens and cornea. The second half of the review describes clinical implications of light/melatonin interactions. These include light exposure and photoreceptor contributions in melatonin suppression, leading to consideration of how blue blockers, cataract, and light therapy might affect sleep and mood in patients. Additionally, the interactions between melatonin, sleep and refractive error development are discussed. A better understanding of environmental factors that affect melatonin and subsequent effects on physiological processes will allow clinicians to develop treatments and recommend modifiable behaviours to improve sleep, increase daytime alertness, and regulate ocular and systemic processes related to melatonin.
89Feasibility and Efficacy of Morning Light Therapy for Adults with Insomnia: A Pilot, Randomized, Open-Label, Two-Arm Study.PubMed
Jihyun Yoon, Seokjae Heo, Hyangkyu Lee, et al.
Medicina (Kaunas). 2023 Jun 1;59(6):1066. doi: 10.3390/medicina59061066.
Light therapy (LT) is used as an adjunctive treatment for sleep problems. This study evaluates the impact of LT on sleep quality and sleep-related parameters in patients with sleep disorders. We performed a pilot, randomized, open-label clinical trial. Fourteen patients aged 20-60 years with insomnia were randomized into the control and LT groups (1:1 ratio). The LT group was instructed to use a device that provides bright LT (6000 K, 380 lux, wavelength 480 nm) for at least 25 min before 09:00 a.m. for two weeks. A self-reported questionnaire was used to evaluate circadian preference, mood, and sleep-related parameters. We analyzed serum cortisol levels and clock genes' expression. The Epworth Sleepiness Scale (ESS), insomnia severity index(ISI), and Pittsburgh Sleep Quality index(PSQI) were significantly improved within the LT group only after the two-week period. When comparing the two groups, only the change in ESS was significant (mean difference, control: -0.14 vs. LT: -1.43, = 0.021) after adjusting for the baseline characteristics. There were no significant differences in serum cortisol or clock genes' expression. LT can improve daytime sleepiness in patients with sleep disorders; however, further well-designed studies are warranted to confirm its efficacy.
90Body temperature and sleep.PubMed
Ronald Szymusiak
Handb Clin Neurol. 2018;156:341-351. doi: 10.1016/B978-0-444-63912-7.00020-5.
Sleep in mammals is accompanied by a decrease in core body temperature (CBT). The circadian clock in the hypothalamic suprachiasmatic nucleus regulates daily rhythms in both CBT and arousal states, and these rhythms are normally coupled. Reductions in metabolic heat production resulting from behavioral quiescence and reduced muscle tone along with changes in autonomic nervous system activity and thermoeffector activity contribute to the sleep-related fall in CBT. Reductions in sympathetic tone to the peripheral vasculature resulting in heat loss through the skin are reflected in a sleep-related increase in distal skin temperature that is a prominent feature of sleep onset in humans. Within a sleep episode, patterns of autonomic nervous system and thermoeffector activity and the ability to defend against heat and cold exposure differ during nonrapid eye movement (NREM) and rapid eye movement sleep. Anatomic and functional integration of the control of arousal states and thermoregulation occur in the preoptic/anterior hypothalamus. Subsets or warm-sensing neurons in the preoptic/anterior hypothalamus implicated in CBT regulation are spontaneously activated during sleep onset and NREM sleep compared to waking and may underlie sleep-related changes in autonomic nervous system and thermoeffector activity.
91Thermoregulation and sleep.PubMed
Pier Luigi Parmeggiani
Front Biosci. 2003 May 1;8:s557-67. doi: 10.2741/1054.
This review describes the systemic physiological phenomena characterizing the interaction between thermoregulatory and sleep processes in the adult mammal. Homeostatic thermoregulation is preserved across the behavioral states of quiet wakefulness and non-rapid eye movement sleep notwithstanding state-dependent differences in threshold and gain of effector responses to thermal loads. In many mammalian species rapid eye movement sleep is characterized by the suppression or depression of thermoregulatory responses to thermal loads. In human adults, however, rapid eye movement sleep is not as thermally altered as in other mammals. The experimental evidence shows that the interaction between thermoregulatory and sleep processes occurs at the level of the preoptic-hypothalamic thermostat. A main open question concerns the nature of the over-riding demand imposing on the central nervous system the temporary suspension of homeostatic integrative regulation in rapid eye movement sleep.
92A warm footbath before bedtime and sleep in older Taiwanese with sleep disturbance.PubMed
Wen-Chun Liao, Ming-Jang Chiu, Carol A Landis
Res Nurs Health. 2008 Oct;31(5):514-28. doi: 10.1002/nur.20283.
A single-group crossover design was used to examine the effects of a warm footbath on body temperatures, distal-proximal skin temperature gradient (DPG), and sleep outcomes in 15 Taiwanese elders with self-reported sleep disturbance. Body temperatures and polysomnography were recorded for three consecutive nights. Participants were assigned randomly to receive a 41 degrees C footbath for 40 minutes before sleep onset on night 2 or night 3. Mean DPG before lights off was significantly elevated on the bathing night. There were no significant differences in sleep outcomes between the two nights. However, when the first two non-rapid eye movement (NREM) sleep periods were examined, the amount of wakefulness was decreased in the second NREM period on the bathing night.
93Before-bedtime passive body heating by warm shower or bath to improve sleep: A systematic review and meta-analysis.PubMed
Shahab Haghayegh, Sepideh Khoshnevis, Michael H Smolensky, et al.
Sleep Med Rev. 2019 Aug;46:124-135. doi: 10.1016/j.smrv.2019.04.008. Epub 2019 Apr 19.
Water-based passive body heating (PBH) as a warm shower or bath before bedtime is often recommended as a simple means of improving sleep. We searched PubMed, CINAHL, Cochran, Medline, PsycInfo, and Web of Science databases and extracted pertinent information from publications meeting predefined inclusion and exclusion criteria to explore the effects of PBH on sleep onset latency (SOL), wake after sleep onset, total sleep time, sleep efficiency (SE), slow wave sleep, and subjective sleep quality. The search yielded 5322 candidate articles of which 17 satisfied inclusion criteria after removing duplicates, with 13 providing comparable quantitative data for meta-analyses. PBH of 40-42.5 °C was associated with both improved self-rated sleep quality and SE, and when scheduled 1-2 h before bedtime for little as 10 min significant shortening of SOL. These findings are consistent with the mechanism of PBH effects being the extent of core body temperature decline achieved by increased blood perfusion to the palms and soles that augments the distal-to-proximal skin temperature gradient to enhance body heat dissipation. Nonetheless, additional investigation is required because the findings regarding PBH are limited by the relative scarcity of reported research, especially its optimal timing and duration plus exact mechanisms of effects.
94Effect of a warm footbath before bedtime on body temperature and sleep in older adults with good and poor sleep: an experimental crossover trial.PubMed
Wen-Chun Liao, Lee Wang, Ching-Pyng Kuo, et al.
Int J Nurs Stud. 2013 Dec;50(12):1607-16. doi: 10.1016/j.ijnurstu.2013.04.006. Epub 2013 May 10.
BACKGROUND: The decrease in core body temperature before sleep onset and during sleep is associated with dilation of peripheral blood vessels, which permits heat dissipation from the body core to the periphery. A lower core temperature coupled with a higher distal (hands and feet) temperature before sleep are associated with shorter sleep latency and better sleep quality. A warm footbath is thought to facilitate heat dissipation to improve sleep outcomes. OBJECTIVES: This study examined the effect of a warm footbath (40°C water temperature, 20-min duration) on body temperature and sleep in older adults (≥55 years) with good and poor sleep. DESIGN: Two groups and an experimental crossover design was used. SETTING AND PARTICIPANTS: Forty-three adults responded to our flyer and 25 participants aged 59.8±3.7 years (poor sleeper with a Pittsburgh Sleep Quality Index score≥5=17; good sleepers with a Pittsburgh Sleep Quality Index score<5=8) completed this study. METHODS: All participants had body temperatures (core, abdomen, and foot) and polysomnography recorded for 3 consecutive nights. The first night was for adaptation and sleep apnea screening. Participants were then randomly assigned to either the structured foot bathing first (second night) and non-bathing second (third night) condition or the non-bathing first (second night) and foot bathing second (third night) condition. RESULTS: A footbath before sleep significantly increased and retained foot temperatures in both good and poor sleepers. The pattern of core temperatures during foot bathing was gradually elevated (poor sleepers vs. good sleepers=+0.40±0.58°C vs. +0.66±0.17°C). There were no significant changes in polysomnographic sleep and perceived sleep quality between non-bathing and bathing nights for both groups. CONCLUSION: A footbath of 40°C water temperature and 20-min duration before sleep onset increases foot temperatures and distal-proximal skin temperature gradients to facilitate vessel dilatation and elevates core temperature to provide heat load to the body. This footbath does not alter sleep in older adults with good and poor sleep.
95Effect of foot bathing on distal-proximal skin temperature gradient in elders.PubMed
Wen-Chun Liao, Carol A Landis, Martha J Lentz, et al.
Int J Nurs Stud. 2005 Sep;42(7):717-22. doi: 10.1016/j.ijnurstu.2004.11.011. Epub 2005 Jan 25.
Increased distal (foot)-proximal (abdominal) skin temperature gradient (DPG) has been associated with better sleep initiation. Warm foot bath can affect distal skin temperature to change DPG. However, the optimum water temperature and duration necessary to raise DPG has not been established. This study explored the effects of 1-h foot bathing at two water temperatures of 40 and 41 degrees C, respectively, on DPG in Taiwanese elders (n=6, ages 60-73 years). Each subject's feet and legs were immersed in a temperature-controlled water tub to 20 cm above the ankles for 60 min in each of two water temperatures. Oral, abdominal, and foot temperatures were taken during (at 10-min intervals), and after (at 1-min intervals) foot bathing. DPG was calculated by subtracting abdominal temperature from foot temperature. Results showed the value of DPG was significantly increased in the 10th min bathing at both water temperatures and maintained above 0 degrees C. DPG gradually declined after bathing at both water temperatures. The value of DPG with 41 degrees C water was slightly higher than 40 degrees C. All subjects tolerated both bathing temperatures well for 1h. Both 40 and 41 degrees C foot bathing for 1h can increase the DPG and may be an effective way to affect whole body skin blood flow and trigger heat dissipation.
96Impact of an intermittent and localized cooling intervention on skin temperature, sleep quality and energy expenditure in free-living, young, healthy adults.PubMed
Huiwen Xu, Antonio Martinez-Nicolas, Wendy D Martinez-Avila, et al.
J Therm Biol. 2021 Apr;97:102875. doi: 10.1016/j.jtherbio.2021.102875. Epub 2021 Feb 19.
Where people live and work together it is not always possible to modify the ambient temperature; ways must therefore be found that allow individuals to feel thermally comfortable in such settings. The Embr Wave® is a wrist-worn device marketed as a 'personal thermostat' that can apply a local cooling stimulus to the skin. The aim of the present study was to determine the effect of an intermittent mild cold stimulus of 25 °C for 15-20 s every 5 min over 3.5 days under free-living conditions on 1) skin temperature, 2) perception of skin temperature, 3) sleep quality and 4) resting energy expenditure (REE) in young, healthy adults. Ten subjects wore the device for 3.5 consecutive days. This intervention reduced distal skin temperature after correcting for personal ambient temperature (P < 0.05), but did not affect the subjects' the perception of skin temperature, sleep quality or REE (all P ≥ 0.051). Thus, this intermittent mild cold regime can reduce distal skin temperature, and wearing it under free-living conditions for 3.5 days does not seem to impair the perception of skin temperature and sleep quality or modify REE.
97Effects of a forehead cooling device in veterans with chronic insomnia disorder and co-morbid medical and psychiatric conditions: a pilot study.PubMed
Vincent Mysliwiec, Thomas C Neylan, Laurel Chiappetta, et al.
Sleep Breath. 2021 Mar;25(1):441-448. doi: 10.1007/s11325-020-02126-w. Epub 2020 Jun 22.
PURPOSE: While forehead cooling has been studied in patients with insomnia in the absence of comorbid medical/psychiatric disorders, it has never been evaluated in patients with insomnia in the presence of co-morbid medical/psychiatric disorders. METHODS: Veterans with chronic insomnia disorder and co-morbid medical and psychiatric conditions received 4-week open-label, in-home, nightly treatment with a forehead cooling device (14-16 °C) along with personalized sleep hygiene following baseline assessments. Pre- and post-treatment, participants completed the Insomnia Severity Index (ISI), the Generalized Anxiety Disorder 7-item scale (GAD-7), and the Patient Health Questionnaire 9-item scale (PHQ-9). Participants recorded daily sleep and anxiety/arousal symptoms. RESULTS: Of 24 veterans (20 men, 42.2 ± 9.5 years), 17 (71%) had marked insomnia severity improvement (a decrease of > 8 on the ISI) and 10 (42%) participants scored 7 or below on the ISI at post-treatment reflecting remission. Participants reported reductions in sleep onset latency (SOL) (F = 12.9, p < 0.001), and wakefulness after sleep onset (WASO) (F = 8.4, p < 0.001) across treatment. They also had significant reductions in insomnia severity (t = 10.04, p < 0.001), anxiety (t = 3.59, p = 0.002), and depression (t = 7.75, p < 0.001) from pre- to post-treatment. CONCLUSION: This pilot study shows that 4-week nightly use of a forehead cooling device produces improvements in insomnia, anxiety, and depressive symptoms in veterans with chronic insomnia disorder and co-morbid medical and psychiatric conditions. Controlled studies are warranted to determine the role of this therapy in the management of insomnia in veterans. TRIAL REGISTRATION: Not required as a small sample size feasibility study.
98Effects of forehead cooling and supportive care on menopause-related sleep difficulties, hot flashes and menopausal symptoms: a pilot study.PubMed
Fiona C Baker, Massimiliano de Zambotti, Laurel Chiappetta, et al.
Behav Sleep Med. 2021 Sep-Oct;19(5):615-628. doi: 10.1080/15402002.2020.1826484. Epub 2020 Oct 10.
OBJECTIVE/BACKGROUND: This pilot study explored the efficacy of a novel forehead cooling device for perceived sleep difficulties and hot flashes in menopausal-age women. PARTICIPANTS: 20 women (55.1 ± 4.2 years; 19 post-menopausal) with insomnia symptoms and self-reported two or more hot flashes per day. METHODS: Participants completed daily assessments of sleep and hot flashes (via diaries) across 1 baseline week and 4 weeks of open-label, in-home, nightly treatment with a forehead cooling device (15-18°C) along with sleep hygiene instructions. They also completed ratings of insomnia and menopausal symptoms using standardized questionnaires. RESULTS: Women reported reductions in sleep onset latency (SOL), wakefulness after sleep onset (WASO), and nocturnal hot flash severity during the first week of treatment (SOL: 25.7 ± 18.4 min; WASO: 36.3 ± 27.3 min; hot flash severity: 3.0 ± 2.8) compared with baseline (SOL: 38 ± 26.3 min; WASO: 52.2 ± 35.6 min; hot flash severity: 6.8 ± 3.7), with further improvements after 2-4 weeks of use ( < .001). There were also clinically meaningful reductions in insomnia severity and hot flash-related daily interference and lower psychological and physical symptom scores on the Greene climacteric scale after treatment (all p's<0.001). CONCLUSIONS: This exploratory, naturalistic, pilot study shows that nightly use of a forehead cooling device produces improvements in self-reported sleep and reductions in insomnia, hot flash, and other menopausal, symptoms. Controlled studies are warranted to determine the role of this therapy in the management of sleep difficulties and menopausal symptoms in women. Further mechanistic studies are needed to understand the physiological impact of forehead cooling on sleep and menopausal symptoms.
99From strain to strength: a yearlong study on the transformative influence of inner engineering online program on mental well-being.PubMed
Ashwin Swaminathan, Braiden DeSchryver, Akila Rayapuraju, et al.
Front Psychol. 2025 Feb 4;16:1436910. doi: 10.3389/fpsyg.2025.1436910. eCollection 2025.
INTRODUCTION: Health is a multidimensional phenomenon encompassing physical, mental, and social well-being, all of which are deeply interconnected. The COVID-19 pandemic highlighted the importance of mental and social health, as rates of loneliness, depression, and anxiety surged. Mindfulness practices, such as Shambhavi Mahamudra Kriya (SMK), have gained attention for their potential to enhance well-being by integrating breath regulation, meditation, and cognitive reframing techniques. During the COVID-19 pandemic, the Inner Engineering Completion Online (IECO) program was created to effectively teach SMK with global travel restrictions in effect. This study examines the long-term effects of SMK, taught through the IECO, on various measures of well-being over a one-year follow-up period. METHODS: Participants were recruited from the January 2020 IECO course. Participants completed surveys at consent, post-IECO, and 6 weeks, 6 months, and 1-year post-IECO. The surveys consisted of 4 validated neuropsychological scales: Perceived Stress Scale (PSS), Positive Emotion/Relationship/Engagement Scale (PERMA) Profiler, Pittsburgh Sleep Quality Index (PSQI), and Mindful Attention Awareness Scale (MAAS). Survey data was analyzed using linear mixed effect modeling. Two-sided -values of <0.05 were considered statistically significant. RESULTS: Hundred and eighty-eight participants were enrolled. Hundred and sixty-four participants completed baseline measurements, and 41 participants completed surveys at all timepoints. The baseline median [IQR] PSS score in participants was 13 [8, 18]; post-IECO median [IQR] PSS was 11 [8, 16] and 6-week median [IQR] PSS was 7 [4, 12], suggesting that consistent practice of Shambhavi Mahamudra Kriya resulted in reduced stress. This score was sustained up to a year post-IECO with a median [IQR] of 7 [3, 12]. The mean mindfulness scale (MAAS) score increased by 0.97 (95% C.I. 0.7-1.2 < 0.01, η = 0.30) at the 1-year timepoint compared to baseline. The global PSQI score reduced at the week 6 timepoint by 1.3 (95% C.I. 0.49-2.0, < 0.01) with medium effect size and was sustained until 1 year. DISCUSSION: Within 6 weeks of participating in IECO, regular practice of SMK significantly reduced stress, improved sleep quality, and boosted mindfulness. These benefits were sustained for at least a year with continued practice, suggesting that this practice is an effective path to maintaining general well-being. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, trial identification number NCT04189146.
100Mindfulness-based interventions for coping with cancer.PubMed
Linda E Carlson
Ann N Y Acad Sci. 2016 Jun;1373(1):5-12. doi: 10.1111/nyas.13029. Epub 2016 Mar 9.
Work in the development and evaluation of mindfulness-based interventions (MBIs) for cancer care has been underway for the last 20 years, and a growing body of literature now supports their efficacy. MBIs are particularly helpful in dealing with common experiences related to cancer diagnosis, treatment, and survivorship, including loss of control, uncertainty about the future, and fears of recurrence, as well as a range of physical and psychological symptoms, including depression, anxiety, insomnia, and fatigue. Our adaptation, mindfulness-based cancer recovery (MBCR), has resulted in improvements across a range of psychological and biological outcomes, including cortisol slopes, blood pressure, and telomere length, in various groups of cancer survivors. In this paper, I review the rationale for MBIs in cancer care and provide an overview of the state of the current literature, with a focus on results from three recent clinical trials conducted by our research group. These include a comparative efficacy trial comparing MBCR to supportive-expressive therapy in distressed breast cancer survivors, a non-inferiority trial comparing MBCR to cognitive behavioral therapy for insomnia in cancer survivors with clinical insomnia, and an online adaptation of MBCR for rural and remote cancer survivors without access to in-person groups. I conclude by outlining work in progress and future directions for MBI research and applications in cancer care.
101The effect of mindfulness meditation on sleep quality: a systematic review and meta-analysis of randomized controlled trials.PubMed
Heather L Rusch, Michael Rosario, Lisa M Levison, et al.
Ann N Y Acad Sci. 2019 Jun;1445(1):5-16. doi: 10.1111/nyas.13996. Epub 2018 Dec 21.
There is a growing interest in the effectiveness of mindfulness meditation for sleep disturbed populations. Our study sought to evaluate the effect of mindfulness meditation interventions on sleep quality. To assess for relative efficacy, comparator groups were restricted to specific active controls (such as evidenced-based sleep treatments) and nonspecific active controls (such as time/attention-matched interventions to control for placebo effects), which were analyzed separately. From 3303 total records, 18 trials with 1654 participants were included. We determined the strength of evidence using four domains (risk of bias, directness of outcome measures, consistency of results, and precision of results). At posttreatment and follow-up, there was low strength of evidence that mindfulness meditation interventions had no effect on sleep quality compared with specific active controls (ES 0.03 (95% CI -0.43 to 0.49)) and (ES -0.14 (95% CI -0.62 to 0.34)), respectively. Additionally, there was moderate strength of evidence that mindfulness meditation interventions significantly improved sleep quality compared with nonspecific active controls at postintervention (ES 0.33 (95% CI 0.17-0.48)) and at follow-up (ES 0.54 (95% CI 0.24-0.84)). These preliminary findings suggest that mindfulness meditation may be effective in treating some aspects of sleep disturbance. Further research is warranted.
102A randomized controlled trial of mindfulness meditation for chronic insomnia.PubMed
Jason C Ong, Rachel Manber, Zindel Segal, et al.
Sleep. 2014 Sep 1;37(9):1553-63. doi: 10.5665/sleep.4010.
STUDY OBJECTIVES: To evaluate the efficacy of mindfulness meditation for the treatment of chronic insomnia. DESIGN: Three-arm, single-site, randomized controlled trial. SETTING: Academic medical center. PARTICIPANTS: Fifty-four adults with chronic insomnia. INTERVENTIONS: Participants were randomized to either mindfulness-based stress reduction (MBSR), mindfulness-based therapy for insomnia (MBTI), or an eight-week self-monitoring (SM) condition. MEASUREMENTS AND RESULTS: Patient-reported outcome measures were total wake time (TWT) from sleep diaries, the pre-sleep arousal scale (PSAS), measuring a prominent waking correlate of insomnia, and the Insomnia Severity Index (ISI) to determine remission and response as clinical endpoints. Objective sleep measures were derived from laboratory polysomnography and wrist actigraphy. Linear mixed models showed that those receiving a meditation-based intervention (MBSR or MBTI) had significantly greater reductions on TWT minutes (43.75 vs 1.09), PSAS (7.13 vs 0.16), and ISI (4.56 vs 0.06) from baseline-to-post compared to SM. Post hoc analyses revealed that each intervention was superior to SM on each of the patient-reported measures, but no significant differences were found when comparing MBSR to MBTI from baseline-to-post. From baseline to 6-month follow-up, MBTI had greater reductions in ISI scores than MBSR (P < 0.05), with the largest difference occurring at the 3-month follow-up. Remission and response rates in MBTI and MBSR were sustained from post-treatment through follow-up, with MBTI showing the highest rates of treatment remission (50%) and response (78.6%) at the 6-month follow-up. CONCLUSIONS: Mindfulness meditation appears to be a viable treatment option for adults with chronic insomnia and could provide an alternative to traditional treatments for insomnia. TRIAL REGISTRATION: Mindfulness-Based Approaches to Insomnia: clinicaltrials.gov, identifier: NCT00768781.
103Enhanced dehydroepiandrosterone levels are positively correlated with N3 sleep stage in long-term mindfulness meditation practitioners.PubMed
Ravindra P Nagendra, Talakad N Sathyaprabha, Bindu M Kutty
Sleep Sci. 2022 Apr-Jun;15(2):179-187. doi: 10.5935/1984-0063.20220039.
OBJECTIVES: Meditation practices positively influence the neural, hormonal and autonomic systems. We have demonstrated that long-term practice of mindfulness meditation increases N3 and rapid eye movement (REM) sleep stages and bring efficient autonomic modulation during sleep. In the present study, the probable humoral correlation that could bring about these changes is evaluated. MATERIAL AND METHODS: Long-term Vipassana meditators (n=41) and controls (n=24) (males, 30-60 years of age) underwent a two-day consecutive whole night polysomnography recording. During the second day, with exposure to 100Lux brightness, blood was sampled from the antecubital vein between 8-9 PM and in subsequent early morning. Sleep stage was scored as per American Society of Sleep Medicine (ASSM) guidelines for the second-day recording. Sleep-related hormones were estimated - melatonin by radioimmunoassay; dehydroepiandrosterone (DHEA), cortisol, growth hormone (GH) and prolactin with enzyme-linked immunosorbent assay (ELISA); DHEA/cortisol ratio was calculated. Percentage of sleep stages and hormonal levels were compared between both groups using independent 't' test and Pearson's correlation was estimated between sleep stages and hormonal levels. RESULTS: Meditators showed increased N3, REM sleep stages. Though evening cortisol was comparable between the two groups; early morning cortisol, diurnal DHEA and melatonin were significantly higher in meditators. Diurnal DHEA correlated significantly with the N3 sleep stage in meditators. DISCUSSION: Higher diurnal DHEA despite variations in corresponding cortisol in meditators demonstrates that long-term Vipassana meditation practice modulates the hypothalamicpituitary-adrenal (HPA) axis and thereby influences sleep. Thus, the study provides evidence to explore the mechanism most likely involved with mindfulness meditation intervention in insomnia.
104Mindfulness is associated with improved psychological well-being but no change in stress biomarkers in breast cancer survivors with depression: a single group clinical pilot study.PubMed
Silja Emilia Sakki, Heidi Marika Penttinen, Outi Maria Hilgert, et al.
BMC Womens Health. 2022 Dec 12;22(1):518. doi: 10.1186/s12905-022-02116-y.
BACKGROUND: The aim of this clinical single group pilot study was to assess mental well-being, psychological symptoms, and a set of stress biomarkers among breast cancer survivors with high depressive symptoms undergoing the Mindfulness-Based Stress Reduction (MBSR) program. METHODS: Participants included 23 curatively treated breast cancer survivors from the Helsinki University Central Hospital with clinically significant symptoms of depression (Beck Depression Inventory > 13, and assessed by a psychiatrist), at 1-year post-operative follow-up. Mental wellbeing and psychological symptoms were assessed with self-reported questionnaires (Resilience Scale, Self-Compassion Scale, Five Facet Mindfulness Questionnaire, World Health Organization Quality of Life-questionnaire, Perceived Stress Scale, Beck Depression Inventory, Beck Anxiety Inventory, Insomnia Severity Index); in addition, stress response was assessed with biomarkers (cortisol, adrenocorticotropine, and high-sensitivity-CRP from blood; 24 h-cortisol from urine). All measures were addressed at baseline, mid-program (4 weeks after baseline) and at the completion of the 8-week MBSR program. Engagement to the independent mindfulness home practice was collected with a diary. RESULTS: From baseline to the completion of the 8-week MBSR program, we observed significant increases in resilience (d = 0.60, p = 0.005), and quality of life (d = 0.92, p = 0.002), and significant reductions in symptoms of depression (d = - 1.17, p < 0.0001), anxiety (d = - 0.87, p < 0.0001), insomnia (d = - 0.58, p = 0.006), and marginally significant reduction in perceived stress (d = - 0.40, p = 0.09). We found no changes in self-compassion or mindfulness skills, nor in the stress biomarkers during or at the completion of the program. There was no association between the engagement time to the independent mindfulness practice and any of the outcomes. CONCLUSIONS: Attending the MBSR program was associated with increased wellbeing and reduced psychological symptoms in breast cancer survivors with clinically significant symptoms of depression. However, these favorably experienced changes did not transfer to the level of stress biomarkers during the 8-week program. Lack of association between the engagement in the mindfulness home practice and change in outcomes suggests that in the studied range of practice time, other qualities of MBSR despite the amount of independent practice may have a more important role for the improved wellbeing. Trial registration ISRCTN12326308 at 16/02/2021, retrospectively registered.
106Benzodiazepine abuse among athletes: Pain relief or just a weapon against insomnia? A clinical case study.PubMed
Lorenzo Zamboni, Fabio Lugoboni, Thomas Zandonai
Scand J Med Sci Sports. 2019 Dec;29(12):1937-1940. doi: 10.1111/sms.13540. Epub 2019 Sep 2.
It is widely recognized that benzodiazepine abuse can potentially induce addiction. Benzodiazepine addiction among athletes is a new and growing phenomenon that we are encountering among our patients. We describe a case of lormetazepam addiction in a female competitive marathon runner. A 30-year-old female elite athlete developed lormetazepam addiction after increasing her daily benzodiazepine dosage in an attempt to achieve better sleep and enhanced performances during training. She was hospitalized for 7 days to undergo benzodiazepine detoxification. Her lormetazepam daily dosage on admission was 18 vials (20 ml × 18 = 360 ml). This report highlights the risk of athletes becoming addicted to benzodiazepines used to combat insomnia and pain. There is a need for clinical and epidemiological research to investigate the effects of this addiction, with a view to better protecting the health of athletes.
107The effect of benzodiazepines on exercise in healthy adult participants: A systematic review.PubMed
Darías Holgado, Agustín Manresa-Rocamora, Lorenzo Zamboni, et al.
J Addict Dis. 2022 Jul-Sep;40(3):336-344. doi: 10.1080/10550887.2021.1990640. Epub 2021 Nov 9.
The use of benzodiazepines among athletes is a new and growing phenomenon according to the recent case reports published. Therefore, there is an urgent need to identify if there is rationale for the use of benzodiazepines and its effects on exercise. This review aims to provide an overview of the effects of benzodiazepine in exercise among healthy adult participants and if they might have an additional ergogenic or ergolytic effect. Electronic searches were conducted in Pubmed, Scopus and Web of Science databases up to December 2020. Search terms covered all active substance names of benzodiazepine class and search terms about sport, exercise performance and athletes. We used the Physiotherapy Evidence Database (PEDro) to assess the methodological quality of the studies included in the qualitative synthesis. The methods and planned analyses of this systematic review were pre-registered at Open Science Framework (OSF: https://osf.io/uq6j8). A total of thirty-one full articles were assessed for eligibility and ten of them were included in the qualitative analysis. We found 7 studies which investigated benzodiazepine effects after an acute dose administered, whereas only 3 studies studied long-term effects after several doses used. According to our findings it does not seem that benzodiazepines might have an ergogenic or ergolytic effect on exercise performance. The small number of articles included ( = 10) with a relatively low sample of participants ( = 16, range = 6-58) does invite us to take our results with caution. This review evidences valuable insights into the use of benzodiazepines from a physical performance point of view. Our findings highlight the unclear effects benzodiazepines might have on exercise performance and its possible mechanisms of actions. Hence, the need to conduct new studies to understand its possible effects becomes essential to protect the health of athletes of all levels.
108Is Melatonin the "Next Vitamin D"?: A Review of Emerging Science, Clinical Uses, Safety, and Dietary Supplements.PubMed
Deanna M Minich, Melanie Henning, Catherine Darley, et al.
Nutrients. 2022 Sep 22;14(19):3934. doi: 10.3390/nu14193934.
Melatonin has become a popular dietary supplement, most known as a chronobiotic, and for establishing healthy sleep. Research over the last decade into cancer, Alzheimer's disease, multiple sclerosis, fertility, PCOS, and many other conditions, combined with the COVID-19 pandemic, has led to greater awareness of melatonin because of its ability to act as a potent antioxidant, immune-active agent, and mitochondrial regulator. There are distinct similarities between melatonin and vitamin D in the depth and breadth of their impact on health. Both act as hormones, affect multiple systems through their immune-modulating, anti-inflammatory functions, are found in the skin, and are responsive to sunlight and darkness. In fact, there may be similarities between the widespread concern about vitamin D deficiency as a "sunlight deficiency" and reduced melatonin secretion as a result of "darkness deficiency" from overexposure to artificial blue light. The trend toward greater use of melatonin supplements has resulted in concern about its safety, especially higher doses, long-term use, and application in certain populations (e.g., children). This review aims to evaluate the recent data on melatonin's mechanisms, its clinical uses beyond sleep, safety concerns, and a thorough summary of therapeutic considerations concerning dietary supplementation, including the different formats available (animal, synthetic, and phytomelatonin), dosing, timing, contraindications, and nutrient combinations.
109Interventions to improve the sleep of nurses: A systematic review.PubMed
Yuan Zhang, Jennifer Murphy, Heidi M Lammers-van der Holst, et al.
Res Nurs Health. 2023 Oct;46(5):462-484. doi: 10.1002/nur.22337. Epub 2023 Sep 14.
Nurses are at a high risk for short sleep duration and poor sleep quality due to irregular work schedules and high occupational stress. Considering the effect of nurses' sleep on the safety and health of themselves and their patients, it is important to promote healthy sleep for nurses. We sought to synthesize the published experimental and quasi-experimental studies that address interventions to improve sleep in nurses. A systematic search was conducted for studies published in English up until May 15, 2023, using the databases PubMed, CINAHL, Academic Search Ultimate, and PsycINFO. In total, 38 articles were included, covering 22 experimental and 16 quasi-experimental studies with sample sizes ranging from 9 to 207. Studies were assessed using the Cochrane Risk of Bias tool and considered as low to medium quality. Thirty-six of the 38 studies reported positive findings for at least one sleep outcome. Intervention types included aroma therapy, dietary supplements, cognitive behavioral therapy, light therapy, mind-body therapy, sleep education, exercise, napping, shift schedule modification, and multicomponent intervention, all of which showed moderate effectiveness in promoting sleep outcomes of nurses. Comparing and contrasting studies on specific interventions for improving sleep in nurses is sparse and often equivocal. With the variations of research methodology and outcome measures, it is difficult to make a conclusion about each intervention's effectiveness on specific sleep outcomes. Additional high-quality research, including randomized controlled trials, is needed to evaluate strategies for improving sleep in this unique, safety-sensitive occupational group.