Deviations from normal bedtimes are associated with short-term increases in resting heart rate

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.

Learning from Large-Scale Wearable Device Data for Predicting the Epidemic Trend of COVID-19

“…e basic anomaly detection method is based on the elevated RHR. Because shortened sleep length also causes an increase in RHR [27], we weaken the contribution of this factor in the physiological anomaly detection method.…”

Day-to-day variability in sleep parameters and depression risk: a prospective cohort study of training physicians

“…However, emerging evidence has identified that stability of the sleep-wake schedule over time is a particularly important contributor to health 3 , 4 . The predictive value of sleep variability has exceeded that of mean levels of sleep parameters in a variety of medical conditions 3 , 5 , 6 .…”

A longitudinal analysis of COVID-19 lockdown stringency on sleep and resting heart rate measures across 20 countries

“…Although these changes were generalized across geographies and cultures, they unwound with easing of lockdowns. www.nature.com/scientificreports/ Later timing of sleep has been associated with higher rates of metabolic dysfunction and cardiovascular disease [47][48][49][50] , while deviations from normal bedtimes have been shown to elevate resting heart rate 51 . There is also a risk that absence or attenuation of social cues together with reduced morning light exposure and increased evening light exposure from screens could lead to a loss of circadian rhythm entrainment 17 .…”