Most people aim for seven to nine hours of sleep and assume that is the main lever they can pull for their health. A large study of nearly 61,000 adults pushes back on that.
Going to bed and waking up at consistent times day after day was a stronger predictor of living longer than sleep duration, researchers reported in the journal Sleep after tracking participants for about seven years.
Higher sleep regularity was linked to a 20% to 48% lower risk of dying from any cause. The link was stronger than the one seen for total hours slept.
Why consistency beat hours
Researchers had participants wear accelerometers on their wrists for a week to build a Sleep Regularity Index. The score runs from 0 to 100.
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A perfect 100 would mean going to bed and rising at exactly the same time each day. In the top-scoring 20%, people fell asleep and woke up within roughly one-hour windows on most of their study days.
Compared with the least regular fifth, more regular sleepers also had a 16% to 39% lower risk of cancer death and a 22% to 57% lower risk of dying from cardiometabolic disease, which covers heart disease, stroke and diabetes. Statistical tests showed regularity outperformed duration as a predictor of all-cause death.
A separate UK Biobank analysis of 88,975 adults, published in eLife, reached the same broad conclusion. People with the most irregular sleep had substantially higher mortality risk than those on steady schedules.
Crucially, the regularity measure carried information about mortality risk that sleep length alone did not.
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A commentary in Sleep put it plainly. Consistency, not duration, was emerging as the stronger predictor of long-term outcomes.
The findings are observational and cannot prove that irregular timing causes early death. But the association held after adjusting for smoking, alcohol, physical activity, existing disease and other common risk factors.
What "regular" looks like in practice
The Sleep Regularity Index reflects habits, not perfection. Missing a bedtime by 15 minutes on a Wednesday will not undo the benefit.
What the top-scoring participants had in common was a bedtime and wake time that held within about a one-hour range on most nights, including weekends.
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That matches long-standing guidance from Harvard Health, which notes that experts have traditionally recommended going to sleep and waking up at the same time every day, including weekends.
Consistent timing anchors the circadian rhythm, the roughly 24-hour internal clock that governs when melatonin, cortisol and body temperature rise and fall.
The practical takeaway is a shift in priority. Someone who sleeps six and a half hours on a steady schedule may fare better on mortality risk than someone averaging eight hours but swinging wildly between weekday and weekend timing.
Trying to make up for lost sleep by sleeping in on weekends, a common workaround, may not close the gap.
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How to anchor your sleep timing
Sleep specialists point to a handful of practical steps for tightening the schedule. Keeping the wake time steady, even on weekends, is often the highest-yield move.
Morning light exposure at a consistent hour is the strongest signal that resets the internal clock, and getting daylight within the first hour of waking reinforces the effect.
Dim indoor lights in the last hour before bed, and avoid caffeine within roughly eight hours of your planned bedtime. Meal timing, exercise timing and screen exposure late at night all influence how easily bedtime falls at the same hour each night.
People with persistent trouble falling asleep at a regular time, or with symptoms of sleep apnea such as loud snoring and daytime fatigue, should talk to their doctor rather than rely on lifestyle changes alone.
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This article is made and published by Jesper Bengtson, who may have used AI in the preparation.