Despite proper sleep hygiene being critical to our health, guidelines for improving sleep habits often focus on only a single component, namely, sleep duration. Recent works, however, have brought to light the importance of another aspect of sleep: bedtime regularity, given its ties to cognitive and metabolic health outcomes. To further our understanding of this often-neglected component of sleep, the objective of this work was to investigate the association between bedtime regularity and resting heart rate (RHR): an important biomarker for cardiovascular health. Utilizing Fitbit Charge HRs to measure bedtimes, sleep and RHR, 255,736 nights of data were collected from a cohort of 557 college students. We observed that going to bed even 30 minutes later than one’s normal bedtime was associated with a significantly higher RHR throughout sleep (Coeff +0.18; 95% CI: +0.11, +0.26 bpm), persisting into the following day and converging with one’s normal RHR in the early evening. Bedtimes of at least 1 hour earlier were also associated with significantly higher RHRs throughout sleep; however, they converged with one’s normal rate by the end of the sleep session, not extending into the following day. These observations stress the importance of maintaining proper sleep habits, beyond sleep duration, as high variability in bedtimes may be detrimental to one’s cardiovascular health.

尽管适当的睡眠卫生对我们的健康至关重要，但改善睡眠习惯的指南通常只关注一个组成部分，即睡眠持续时间。然而，最近的研究揭示了睡眠另一个方面的重要性：就寝时间规律性，因为它与认知和代谢健康结果有关。为了进一步了解睡眠中这一经常被忽视的组成部分，这项工作的目的是调查就寝时间规律性与静息心率 (RHR) 之间的关联：这是心血管健康的重要生物标志物。利用 Fitbit Charge HR 测量就寝时间、睡眠和 RHR，从 557 名大学生中收集了 255,736 个晚上的数据。我们观察到，即使比正常就寝时间晚 30 分钟上床睡觉，也会导致整个睡眠期间的 RHR 显着升高（Coeff +0.18；95% CI：+0.11，+0.26 bpm），这种情况持续到第二天并与正常值趋同傍晚时分 RHR。至少提前 1 小时就寝时间也与整个睡眠期间 RHR 显着升高有关；然而，在睡眠结束时，它们会恢复到正常水平，不会延续到第二天。这些观察强调了在睡眠时间之外保持适当睡眠习惯的重要性，因为就寝时间的高度变化可能不利于心血管健康。