Abstract
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.
Highlights
Prolonged inadequate sleep habits have been repeatably linked to serious medical conditions such as heart disease, obesity and decreased life expectancy[1,2,3]
The observations from this work suggest deviations from an individual’s normal bedtime may prohibit resting heart rate (RHR) from slowing to its normal pace, resulting in a higher RHR throughout one’s sleep session. This short-term change to RHR may persist into the following day, with RHR returning to its normal pace by early evening
This extension only manifests when individuals go to bed later than their normal bedtime as opposed to earlier
Summary
Prolonged inadequate sleep habits have been repeatably linked to serious medical conditions such as heart disease, obesity and decreased life expectancy[1,2,3]. To improve our sleep habits, we are often recommended to achieve 7–9 h of sleep per night[4]; this goal alone neglects a less understood, yet critical aspect of proper sleep: bedtime regularity. Prior research has observed that large differences in bedtime regularity, even after adjusting for bedtime duration, are linked to worsened health outcomes, for our cognitive and metabolic systems[5,6,7]. The literature has yet to address, what these disparities in bedtime regularity mean for our cardiovascular health. As such, this manuscript serves to address this gap: examining how adherence to a normal bedtime is associated with resting heart rate (RHR)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
