Schlichtiger Jenny, Brunner Stefan, Strüven Anna, Hoppe John Michael, Stremmel Christopher
Department of Medicine I, LMU University Hospital, LMU Munich, 81377 Munich, Germany.
DZHK (German Centre for Cardiovascular Research), Partner Site Munich Heart Alliance, LMU University Hospital, LMU Munich, 81377 Munich, Germany.
Nutrients. 2025 Apr 29;17(9):1503. doi: 10.3390/nu17091503.
Chronic sleep deprivation can lead to adverse health effects and therefore represents a public health burden While caffeine is a widely used stimulant, the relationship between caffeine consumption and sleep remains uncertain. Moreover, many studies might be subject to methodological bias, as invasive sleep measurements may themselves serve as confounders. The aim of the SleepSmart study was to assess the impact of caffeine consumption through coffee and energy drinks, utilizing both smartwatch data and questionnaire responses. The SleepSmart study is an observational cohort study conducted at LMU Hospital Munich, Germany, from July 2024 to January 2025. The study investigated two intervention groups: (1) coffee and (2) energy drink consumption. Each intervention lasted 1 week, with days 1 to 3 serving as a reference period (water consumption to adjust for increased fluid intake) and days 4 to 6 serving as the intervention period (consumption of an equivalent of 240 mg of caffeine per day, 3 h before bedtime). Data was collected through self-administered questionnaires and wearable devices. The primary endpoint was sleep duration. Objective measures of sleep (duration of light/deep sleep, duration of wake phases, heart rate) and self-assed quality of sleep (Pittsburgh Sleep Quality Index) served as secondary endpoints. For the primary endpoint, we did not find a significant difference in average sleep duration (baseline [hours] 6.7, coffee 6.9, energy drink 6.7, -value 0.183). Similarly, secondary endpoints related to sleep measures showed no significant changes in the duration of light/deep sleep (coffee [min]: 242.2, reference coffee [ref] 255.7 I energy drink: 237.5, reference energy drink [ref] 261.3), time awake (coffee 22.7, ref 23.4 I energy drink 21.3, ref 18.9), time to fall asleep/wake up (coffee 4.2, ref 4.0 I energy drink 4.4, ref 2.7), or average heart rate (coffee [bpm] 62.2, ref 62.1 I energy drink 62.6, ref 62.3)-neither between the two intervention groups nor compared to the reference period. However, self-assessed sleep quality revealed a decrease in perceived sleep quality, with reports of poor sleep increasing by 8% after coffee consumption (rather bad/very bad sleeping quality: 29.7%) and 20% after energy drink consumption (46.6%), compared to baseline data (21.6%). The SleepSmart study introduces wearable sleep tracking as an innovative, low-interference method for objectively recording sleep data. While wearable data did not indicate significant sleep deterioration in the group of young, healthy adults, caffeine appeared to negatively impact the subjective perception of sleep in the study cohort.
长期睡眠不足会对健康产生不利影响，因此是一项公共卫生负担。虽然咖啡因是一种广泛使用的兴奋剂，但咖啡因摄入与睡眠之间的关系仍不确定。此外，许多研究可能存在方法学偏差，因为侵入性睡眠测量本身可能就是混杂因素。“智能睡眠”研究的目的是利用智能手表数据和问卷调查结果，评估通过咖啡和能量饮料摄入咖啡因的影响。“智能睡眠”研究是一项于2024年7月至2025年1月在德国慕尼黑路德维希 - 马克西米利安大学医院进行的观察性队列研究。该研究调查了两个干预组：（1）咖啡组和（2）能量饮料组。每次干预持续1周，第1至3天作为参考期（饮用清水以适应液体摄入量增加），第4至6天作为干预期（睡前3小时每天饮用相当于240毫克咖啡因的饮品）。数据通过自我填写的问卷和可穿戴设备收集。主要终点是睡眠时间。睡眠的客观指标（浅睡眠/深睡眠时长、清醒阶段时长、心率）和自我评估的睡眠质量（匹兹堡睡眠质量指数）作为次要终点。对于主要终点，我们未发现平均睡眠时间有显著差异（基线[小时]6.7，咖啡组6.9，能量饮料组6.7，P值0.183）。同样，与睡眠测量相关的次要终点在浅睡眠/深睡眠时长（咖啡组[分钟]：242.2，参考咖啡组[ref]255.7；能量饮料组：237.5，参考能量饮料组[ref]261.3）、清醒时间（咖啡组22.7，ref 23.4；能量饮料组21.3，ref 18.9）、入睡/醒来时间（咖啡组4.2，ref 4.0；能量饮料组4.4，ref 2.7）或平均心率（咖啡组[每分钟心跳数]62.2，ref 62.1；能量饮料组62.6，ref 62.3）方面，两个干预组之间以及与参考期相比均未显示出显著变化。然而，自我评估的睡眠质量显示，睡眠质量的感知有所下降，与基线数据（21.6%）相比，饮用咖啡后睡眠质量差的报告增加了8%（睡眠质量相当差/非常差：29.7%），饮用能量饮料后增加了20%（46.6%）。“智能睡眠”研究引入了可穿戴睡眠追踪技术，作为一种创新的、低干扰的方法来客观记录睡眠数据。虽然可穿戴数据未表明年轻健康成年人组的睡眠有显著恶化，但咖啡因似乎对研究队列中的睡眠主观感受产生了负面影响。
