A Consistent Sleep Schedule Is More Important Than How Long You Sleep, Study Finds

New Year’s resolution idea: Try to go to bed and wake up at the same time every single day.

Getting enough sleep—that’s seven to nine solid hours a night, according to sleep health recommendations—is an important factor for overall health, from cognitive functioning to mood management and immunity. A wealth of sleep research has found strong associations between sleep duration (how long we sleep for) and all-cause mortality risk. Both sleeping too little and sleeping too much—either less or more than the recommended seven-to-nine hours per night—has been associated with higher mortality risk. It’s no wonder health experts so eager to convey the importance of clocking this sweet-spot amount of nightly shut-eye.

Sleep Regularity Study and Findings

But a recent 2023 study published in Sleep adds another piece to the complex sleep health puzzle: That sleep regularity, “defined as the day-to-day consistency of sleep-wake timing,” may be an even stronger predictor for mortality risk and certain health outcomes than average sleep length. So going to bed and waking up at a consistent time every day and night is, perhaps, an even better goal to aim for when trying to improve sleep hygiene, habits, and health.

Researchers from Harvard University and Monash University in Melbourne, Australia, calculated Sleep Regularity Index (SRI) scores based on sleep and general health data from over 60,000 U.K. Biobank participants. Overall, they found that, compared to those with the least-regular sleep schedules, participants with the most regular, day-to-day fall-asleep and wakeup patterns had a 20- to 40-percent lower risk of death by any cause; a 16- to 39-percent lower risk of death from cancer; and a 22- to 57-percent lower risk of death by cardiometabolic conditions.

What exactly counts as a “regular” sleep schedule? In this case, participants who fell into the top 20 percent of SRI scores fell asleep and woke up within about the same one-hour windows each morning and night (during the study). For example, they might always fall asleep anywhere between 10 p.m. and 11 p.m. and always awake between 7 a.m. and 8 a.m. On the other hand, those with the lowest sleep regularity scores went to bed and got up the next morning within roughly three-hour windows (e.g. they go to sleep sometime between 10 p.m. and 1 a.m., or wake up anywhere between 7 a.m. and 10 a.m.).

Related: Practice the Military Sleep Method to Fall Asleep in Mere Minutes (Naturally)

How to Make Your Sleep Schedule More Consistent

A consistent sleep schedule is crucial for honoring and regulating your body’s natural circadian rhythm, the internal 24-hour (ish) clock that influences not only sleepiness and wakefulness, but energy levels, appetite, metabolism, and much more.

Since it’s harder to control when you fall asleep—though there are many healthy habits and helpful tricks to get you there—you do have more control over your wakeup times. If you get up consistently at 7 a.m., for example, your body will eventually adjust to this wakeup time and learn to become sleepy and shut down at a consistent time each night. (This goes for both early birds and night owls—people’s chronotypes vary widely, so work with your own body, lifestyle, and schedule). While it’s tempting (and sometimes necessary!) to sleep in a bit over the weeks, on vacation, or during a holiday, try not to let your morning wakeup times extend by more than an hour.

Related: 7 Factors That Affect Your Natural Sleep-Wake Cycle

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