School of Medicine, Department of Emergency Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania.
School of Health and Rehabilitation Sciences, Emergency Medicine Program, University of Pittsburgh, Pittsburgh, Pennsylvania.
Prehosp Emerg Care. 2023;27(6):815-824. doi: 10.1080/10903127.2023.2227891. Epub 2023 Jul 17.
Blunting of the sleep-related dip in blood pressure (BP) has been linked to numerous cardiovascular outcomes including myocardial infarction. Blunting of BP dipping occurs during night shift work and previous research suggest that a 60-min or longer on-shift nap is needed to restore normal/healthy BP dipping. We sought to determine the effect of different durations of napping on BP during and following simulated night shifts. We hypothesized that the greatest benefit in terms of restoration of normal BP dipping during night shift work would be observed during a longer duration nap versus a shorter nap opportunity.
We used a randomized crossover laboratory-based study design. Participants consented to complete three separate 72-hr conditions that included a 12-hr simulated night shift. Nap conditions included a 30-min and 2-hr nap compared to a no-nap condition. Ambulatory BP monitoring was assessed hourly and every 10-30 mins during in-lab naps. Blunted BP dipping during in-lab naps was the primary outcome. Goal enrollment of 25 (35 with attrition) provided 80% power to detect a mean difference of 5 mmHg in BP between nap conditions.
Of the 58 screened, 28 were consented, and 26 completed all three 72-hr conditions. More than half (53.6%) were female. Mean age was 24.4 years (SD7.2). Most (85.7%) were certified as emergency medical technicians or paramedics. The mean percentage dip in systolic BP (SBP) and diastolic BP (DBP) did not differ between the 30-min and 2-hr nap conditions ( > 0.05), yet a greater proportion of participants experienced a 10-20% dip in SBP or DBP during the 2-hr nap versus the 30-min nap ( < 0.05). For every additional minute of total sleep during the 30-min nap, the percentage of SBP dip improved by 0.60%, and the percentage of DBP dip improved by 0.68% ( < 0.05). These improvements approximate to a 6% per minute relative advancement toward normal/healthy BP dipping.
Restoration of a normal/healthy dip in BP is achievable during short and long duration nap opportunities during simulated night shift work. Our findings support the hypothesis that BP dipping is more common during longer 2-hr versus shorter 30-min naps.
ClinicalTrials.gov, NCT04469803. Registered on 9 July 2020.
血压（BP）与睡眠相关的下降幅度变平与许多心血管结局有关，包括心肌梗死。夜间轮班工作时会出现 BP 下降幅度变平，之前的研究表明，需要进行 60 分钟或更长时间的轮班小睡，才能恢复正常/健康的 BP 下降幅度。我们试图确定在模拟夜间轮班期间和之后，不同时长小睡对 BP 的影响。我们假设，在夜间轮班工作期间，较长时间的小睡相对于较短的小睡机会，对恢复正常 BP 下降幅度的益处最大。
我们使用了随机交叉实验室基础研究设计。参与者同意完成三个单独的 72 小时条件，包括 12 小时模拟夜间轮班。小睡条件包括 30 分钟和 2 小时小睡，与无小睡条件相比。每小时和在实验室小睡期间每 10-30 分钟进行动态血压监测。实验室小睡期间血压下降幅度变平是主要结果。目标入组 25 人（35 人因脱落），可提供 80%的效能，以检测小睡条件之间 BP 平均差异 5mmHg。
在 58 名筛选者中，有 28 名同意参与，其中 26 名完成了所有三个 72 小时的条件。超过一半（53.6%）为女性。平均年龄为 24.4 岁（SD7.2）。大多数（85.7%）是经过认证的急救医疗技术员或护理人员。收缩压（SBP）和舒张压（DBP）的平均下降百分比在 30 分钟和 2 小时小睡条件之间没有差异（>0.05），但在 2 小时小睡时，有更大比例的参与者出现 SBP 或 DBP 下降 10-20%（<0.05）。在 30 分钟小睡期间，每增加 1 分钟总睡眠时间，SBP 下降百分比增加 0.60%，DBP 下降百分比增加 0.68%（<0.05）。这些改善相当于每分钟 BP 下降幅度向正常/健康方向进展 6%。
在模拟夜间轮班工作期间，短时间和长时间小睡都可以恢复正常/健康的 BP 下降幅度。我们的研究结果支持以下假设，即在 2 小时的小睡中，BP 下降幅度比 30 分钟的小睡更常见。
ClinicalTrials.gov，NCT04469803。于 2020 年 7 月 9 日注册。
