Regularity

• Light

  Keep the bedroom dark and get daylight early.

• Weekends

  Keep your bedtime steady, weekends included.

What It Is

The day-to-day consistency of when you fall asleep and wake up.

Why It Matters

Sleep regularity, the consistency of your sleep and wake times from one day to the next, is a distinct dimension of sleep health, separate from how long or how well you sleep. The evidence suggests that more regular sleep may carry lower all-cause mortality, and one large cohort found regularity predicted mortality at least as well as sleep duration did. It is also a leading indicator you can directly control.

That evidence is thinner than its consistency makes it look. It leans heavily on one group of middle-aged adults who wore a wrist accelerometer for a single week, studied against one outcome after another, so the agreement is across outcomes rather than across populations. How regularity is scored is not standardized either, and when researchers recomputed the same index on the same participants using two accepted methods, one found a link to mortality and the other found none. The likely mechanism is circadian disruption, where shifting your sleep timing from day to day pulls the internal clock out of alignment with its environment.

What to aim for is straightforward regardless: keep your bedtime and wake time within a narrow window every day, including weekends. Large shifts on days off, sometimes called social jetlag, are the most common source of irregularity, and the largest of those shifts track higher cardiovascular risk regardless of how long you sleep. Sleeping in at the weekend does not repay the debt either, and in adults followed with wrist trackers, weekend catch-up sleep carried no measurable benefit. Consistency matters more than perfection, so aim for a stable rhythm rather than an identical schedule to the minute.

• Huang, T. et al. (2020). Sleep irregularity and risk of cardiovascular events: the Multi-Ethnic Study of Atherosclerosis. Journal of the American College of Cardiology. doi.org/10.1016/j.jacc.2019.12.054
• Sletten, T.L. et al. (2023). The importance of sleep regularity: a consensus statement of the National Sleep Foundation sleep timing and variability panel. Sleep Health. doi.org/10.1016/j.sleh.2023.07.016
• Cribb, L. et al. (2023). Sleep regularity and mortality: a prospective analysis in the UK Biobank. eLife. doi.org/10.7554/eLife.88359
• Windred, D.P. et al. (2024). Sleep regularity is a stronger predictor of mortality risk than sleep duration: A prospective cohort study. Sleep. doi.org/10.1093/sleep/zsad253
• Chaput, J.P. et al. (2024). Device-measured weekend catch-up sleep, mortality, and cardiovascular disease incidence in adults. Sleep. doi.org/10.1093/sleep/zsae135
• Kalkanis, A. et al. (2025). Sleep regularity as an important component of sleep hygiene: a systematic review. Sleep Medicine Reviews. doi.org/10.1016/j.smrv.2025.102203
• Chaput, J.P. et al. (2025). Sleep regularity and major adverse cardiovascular events: a device-based prospective study in 72 269 UK adults. Journal of Epidemiology and Community Health. doi.org/10.1136/jech-2024-222795
• Kumar, N., Krishnamurthy, S. (2026). Social jet lag is associated with incident cardiovascular disease independent of sleep duration and cardiac genetic risk. Journal of Internal Medicine. doi.org/10.1111/joim.70133
• Czeisler, M.É. et al. (2026). Comparison of Sleep Regularity Index scores calculated by open-source packages and implications for outcomes research: rationale and design of the RIRI statement (Reporting Items for Regularity Indices). Sleep. doi.org/10.1093/sleep/zsaf299