Sleep advice tends to fixate on one number, hours per night. A large study of nearly 61,000 adults now suggests the clock is at least as important.
People with the most consistent sleep and wake times had a 20 to 48 percent lower risk of dying from any cause over the follow-up period than people with the most erratic schedules.
The analysis of UK Biobank data, published in the journal Sleep in September 2023, tracked 60,977 participants with an average age of 62.8 for a mean of 6.3 years.
Sleep patterns were captured objectively with wrist accelerometers, then scored on the Sleep Regularity Index, a 0 to 100 scale where higher numbers mean more day-to-day similarity in when you fall asleep and wake up.
The comparison between regularity and duration was the striking part. When the researchers pitted the two against each other in statistical models, sleep regularity was the stronger predictor of all-cause mortality.
Similar patterns showed up for cardiometabolic deaths, where the most regular sleepers had a 22 to 57 percent lower risk, and cancer deaths, where the reduction was 16 to 39 percent.
Why timing shapes health
The National Sleep Foundation reviewed the wider evidence and reached the same conclusion. Its expert panel gave the highest possible appropriateness rating to the statement that daily regularity in sleep timing is important for health, in a consensus published in September 2023.
"Consistent timing of bedtimes and wake times are associated with improved outcomes across multiple dimensions of health and performance," said Charles A. Czeisler, the panel chair and Division Chief of Sleep and Circadian Disorders at Brigham and Women's Hospital.
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The panel linked irregular sleep to obesity, diabetes, cardiovascular disease, immune dysfunction, cancer and mental health problems.
The link with anxiety and depression
Mortality is not the only signal. A separate 2025 UK Biobank analysis of 79,666 adults, published in August 2025, followed people who did not have depression or anxiety at the start and tracked new diagnoses.
Regular sleepers had a 38 percent lower risk of developing depression and a 33 percent lower risk of anxiety than those with irregular patterns, after adjustment. Strikingly, participants who slept the recommended number of hours but did so on an inconsistent schedule still had a 48 percent higher depression risk than regular sleepers.
What "regular" looks like in practice
The findings are observational, so they do not prove that steady bedtimes cause longer or healthier lives.
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The authors of the mortality study concluded that sleep regularity may be a simple, effective target for improving general health and survival, and both papers point in the same direction as the National Sleep Foundation guidance.
For most adults, the foundation still recommends 7 to 9 hours of sleep per night.
Its guidance now sits alongside a second point - keep the timing similar from day to day, weekends included.
If weekday sleep runs short, an extra 1 to 2 hours on non-work days can help most people catch up.
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Anyone with persistent insomnia or symptoms of depression or anxiety should raise it with a doctor rather than try to self-manage.
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