Sleep and lifespan

In the Wisconsin Sleep Cohort, adults with untreated severe sleep-disordered breathing had about 3 times the all-cause mortality of those without it over 18 years of follow-up, after adjusting for age, sex, and body mass [2]. Long-term series of men with severe apnea show far fewer fatal and non-fatal cardiovascular events in those treated with CPAP than in those left untreated [8]. No other sleep exposure on this page comes close to that multiplier, and most people who have it do not know.

In 172,321 US adults from the National Health Interview Survey, followed to 2019, people with all five low-risk sleep traits (7 to 8 hours, rarely trouble falling asleep, rarely trouble staying asleep, waking rested most days, no sleep medication) had 30% lower all-cause mortality, 21% lower cardiovascular and 19% lower cancer mortality than people with zero or one trait. Life expectancy at 30 was 4.7 years longer for men and 2.4 for women, and 7.9% of all deaths in the cohort were attributable to suboptimal sleep patterns [1].

In 60,977 UK Biobank participants wearing wrist accelerometers, a sleep regularity index (how similar each night is to the last) predicted all-cause mortality more strongly than sleep duration: the most regular sleepers had 20 to 48% lower death risk than the least regular [4]. Cardiometabolic and cancer mortality followed the same gradient. The circadian system runs every organ, and a different schedule each day is a low-grade jet lag it never adapts to.

Across 16 prospective cohorts and 1.3 million people, habitual sleep under about 6 hours was associated with 12% higher all-cause mortality, and over 9 hours with about 30% higher [5]. In 231,048 Australians followed for 6 years, short sleep alone carried a 9% higher hazard and long sleep 44% [9]. Long sleep mostly marks illness already under way, depression, and inflammation rather than causing death; short sleep raises blood pressure and blunts glucose control within days in lab studies.

The chart above is the honest ranking. Among 19,951 US adults followed for a median 7.6 years, falling short on each Life’s Essential 8 metric accounted for a measured share of deaths: physical activity 16.5%, nicotine 14.7%, diet 11%, blood pressure 5.8%, sleep 5.4%, blood glucose 4.7%, with the whole score together explaining 33.4% [6]. Sleep there was scored only by hours, so this understates apnea and regularity, but the order is the point: sleep is a lever, not the lever.

In 7,959 Whitehall II participants followed for 25 years, sleeping 6 hours or less at age 50 and at 60 was associated with 22% and 37% higher dementia incidence than 7 hours, and persistently short sleep across 50, 60 and 70 with 30% higher risk, independent of cardiometabolic and mental health factors [7]. The 2024 Lancet Commission did not add sleep to its 14 dementia factors, judging the evidence still too tangled with early disease, so read this as strong observational, not settled.

In 1,969 older Australians followed for a median 9.2 years, night-time insomnia symptoms alone (trouble falling or staying asleep) were not associated with higher mortality, but daytime symptoms (fatigue, poor concentration, low function) were, with 66% higher death risk in the worst fifth versus the best [3]. The lesson for the anxious sleeper is a relief: a bad night is not the danger. Days that no longer work are the signal.

A meta-analysis of 11 cohorts found daytime naps of an hour or longer associated with higher cardiovascular disease and all-cause mortality, while naps under 30 minutes carried no such signal [11]. Long naps are usually the shadow of short or broken nights, or of apnea, rather than a cause on their own.

In 4,824 US adults in the Sleep Heart Health Study followed for about 11 years, going to bed after midnight was linked to 53% higher all-cause mortality and going to bed by 10 pm to 23% higher, versus a bedtime between 10 pm and midnight, after adjusting for sleep duration, apnea severity, insomnia symptoms and heart disease. Among older US men the late-bedtime link held (27% higher) but the early one did not [12]. Across 112,198 people in 21 countries, bedtimes before 10 pm and after midnight were both linked to about 10% more deaths and major heart events in the fully adjusted model [13].

Pooled across 10 cohorts and 73,702 people, poor subjective sleep quality went with 3% higher all-cause mortality, too small to tell from zero, though it was linked to 44% more coronary heart disease [14]. Social jetlag, sleeping on a later clock at weekends, has no mortality study yet; a two-hour or larger weekday-to-weekend shift was linked to 30% more incident cardiovascular disease in 51,562 UK Biobank adults, independent of sleep duration [15].