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Sleep duration: the U-shaped longevity curve

Each row is one study of death risk from sleep duration. The bright line is what that study found. The band around it is the range the data still supports — it fades where the evidence thins. Left of the centre line is lower risk.

what the study foundstill plausibleno change
short sleep (<7 h vs 7–8 h)
Ungvari et al. 2025
14% higher
range 10–18% higher
long sleep (≥9 h)
Ungvari et al. 2025
34% higher
range 26–42% higher
short sleep
Cappuccio et al. 2010
12% higher
range 6–18% higher
long sleep
Cappuccio et al. 2010
30% higher
range 22–38% higher

Death risk is lowest at 7 hours. Shorter or longer sleep is worse. Solid line is Yin 2017 Table 2 on both sides — the short side is almost flat. Dashed line is the engine’s steeper 6% per hour below 7.

0%10%20%30%40%4567 hours89108%4%1%4%15%32%19%12%6%

hours of sleep · % higher death risk vs 7 hours

What it is

Sleep duration is your typical nightly hours of sleep. Both too little and too much are associated with worse outcomes.

Why it matters for longevity

The engine is Yin 2017 (generally healthy adults, nadir ≈7 h). Duration is U-shaped: short and long both raise ACM, so the forest plot shows the categorical pair, not a single HR. Regularity is the stronger ACM predictor in the same construct family (Windred 2024) — see Sleep Regularity. Long-side anchors 8 / 9 / 10 h = RR 1.04 / 1.15 / 1.32 are Table 2 (40 ACM risk estimates), not the 57-report extreme-categorical pooling. Short-side 6 / 5 / 4 h = 1.06 / 1.12 / 1.19 apply Yin’s linear 1.06 per hour below 7 h — Table 2’s nonlinear short side is flatter (1.01 / 1.04 / 1.08). Overlay: Yin. Under: Ungvari 2025 (meta — 79-cohort categorical short 1.14 / long 1.34 vs 7–8 h, not a dose–response) / Kwok 2018 (competing — 30-study dose–response, no significant increase below 7 h) / Cappuccio 2010 (action — old 1.12 / 1.30 categorical pairing, not the engine and not a sleep-extension trial). PCHIP interiors are constructed. Engine not moved.

How to improve it

  • Keep a consistent sleep and wake time
  • Get morning light; dim screens in the evening
  • Keep the bedroom cool, dark and quiet

Evidence, by endpoint

EndpointGradeFinding
All-cause mortalityB
7 h = 1.0 (Yin 2017)
Nadir ≈7 h. Table 2 long side: 8 h RR 1.04, 9 h 1.15, 10 h 1.32. That is 40 ACM risk estimates, not the 57-report shortest/longest pooling.
—METHOD
Short side is the linear slope, not Table 2
Engine 4 / 5 / 6 h = 1.19 / 1.12 / 1.06 from Yin’s 1.06 per hour below 7 h. Table 2’s nonlinear short side is 1.08 / 1.04 / 1.01. Kwok 2018 found no significant increase below 7 h. Engine not moved.
All-cause mortalityC
Short/Long Categorical, Not the Curve (Ungvari 2025)
79-cohort pooling (search to Oct 2024): short sleep (<7 h vs 7–8 h) ACM HR 1.14 (1.10–1.18); long sleep (≥9 h) HR 1.34 (1.26–1.42). Categorical, not a dose-response — this calculator uses Yin’s curve instead. Note: the first author is editor-in-chief of the publishing journal.
Nighttime sleep vs all-cause mortalityB
1.55 at 11 Hours, Nighttime Only (Shen 2016)
Pooling 35 articles (146,830 deaths across 1,526,609 people), nighttime sleep vs a 7 h reference: 4 h carried ACM RR 1.07 (1.03–1.13), 6 h was flat at 1.01, and 11 h rose to 1.55 (1.47–1.63). The 24-hour-sleep column in the same paper is different and higher at 11 h (RR 1.84) — nighttime and 24-hour totals are not interchangeable.
All-cause mortality, women onlyB
Short Sleep Only Significant in Women (Liu 2016)
Flexible non-linear meta-regression of 40 cohorts (2,200,425 people, 271,507 deaths): 24-hour sleep of 4 h carried ACM RR 1.05 (1.02–1.07) and 11 h carried RR 1.38 (1.33–1.44) versus 7 h. In sex-stratified analysis the short-sleep mortality signal held for women but was not significant for men.
All-cause mortalityC
The Original 1.12 / 1.30 Pair (Cappuccio 2010)
Foundational categorical pooling of 16 studies / 27 cohorts (1,382,999 people, 112,566 deaths), not a dose-response curve: short sleep carried ACM RR 1.12 (1.06–1.18) and long sleep RR 1.30 (1.22–1.38) versus the reference band — the pair this page used to lead with, before Yin’s finer-grained curve became the engine.

What argues against this

Kwok et al. 2018 (74-study review; dose-response analysis of 30 studies, >1 million people, slot: competing) found no significant increase in all-cause mortality below 7 hours of sleep, directly undercutting the short-side slope this calculator takes from Yin 2017 (1.06 per hour below 7h, pricing 4/5/6h at HR 1.19/1.12/1.06). Kwok's long side sits close to Yin's Table 2, so the disagreement is confined to whether short sleep carries any real mortality penalty at all.

Last reviewed 2 September 2026

Evidence

  1. Yin et al. (2017) — Journal of the American Heart Association
    Relationship of Sleep Duration With All-Cause Mortality and Cardiovascular Events: A Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies
    View source
  2. Ungvari et al. (2025) — GeroScience
    Imbalanced sleep increases mortality risk by 14–34%: a meta-analysis
    View source
  3. Kwok et al. (2018) — Journal of the American Heart Association
    Self-Reported Sleep Duration and Quality and Cardiovascular Disease and Mortality: A Dose-Response Meta-Analysis
    View source
  4. Shen et al. (2016) — Scientific Reports
    Nighttime sleep duration, 24-hour sleep duration and risk of all-cause mortality among adults: a meta-analysis of prospective cohort studies
    View source
  5. Liu et al. (2016) — Sleep Medicine Reviews
    Sleep duration and risk of all-cause mortality: A flexible, non-linear, meta-regression of 40 prospective cohort studies
    View source
  6. Cappuccio et al. (2010) — Sleep
    Sleep duration and all-cause mortality: a systematic review and meta-analysis of prospective studies
    View source
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