← All metrics

Why sleep regularity may matter more than duration

Each row is one study of death risk from sleep regularity. 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
most-regular (80–100th) vs least (0–20th)
Windred et al. 2024
30% lower
range 17–41% lower
irregular vs regular
Omichi et al. 2022
30% higher
range 18–44% higher
regular-optimal vs irregular-insufficient sleep pattern (actigraphy clusters, combines duration and regularity)
Chung et al. 2023
39% lower
range 17–55% lower

What it is

Sleep regularity is how consistent your sleep and wake times are from day to day. This calculator asks a five-level self-report and maps it onto Windred 2024’s Sleep Regularity Index quintiles — it does not compute an SRI from a wearable.

Why it matters for longevity

The engine is Windred 2024 (UK Biobank accelerometer SRI, n=60,977). Least-regular quintile = HR 1.0. Most-regular (80–100th vs 0–20th) fully adjusted ACM HR 0.70 (0.59–0.83). The 0.52 (0.45–0.60) on older pages is the same contrast in the minimal model — not used. Interiors 0.91 / 0.84 / 0.76 are log-linear fill, not Table 2. Kalkanis 2025 (59 studies, search to July 2025) is a systematic review, not a meta: heterogeneity of metrics precluded pooling; five low-bias cohorts narratively showed 20–88% higher ACM for the least regular. Cribb 2023 is the same UK Biobank wave against the median SRI (5th percentile HR 1.53), a different pipeline and comparator. Omichi 2022 (self-report, Japan) HR 1.30 irregular vs regular. Chung 2023 mixes duration with regularity. Engine not moved.

How to improve it

  • Anchor a fixed wake time, even on weekends
  • Keep bedtime within a ~1-hour window
  • Use morning light to stabilize your rhythm

Evidence, by endpoint

EndpointGradeFinding
All-cause mortalityC
0.70, not 0.52 (Windred 2024)
Most-regular vs least-regular quintile: fully adjusted ACM HR 0.70 (0.59–0.83). 0.52 is the minimal model at the same contrast. This calculator uses 0.70.
All-cause mortalityC
No matching-construct meta (Kalkanis 2025)
59-study systematic review, search to July 2025: heterogeneity of metrics precluded meta-analysis. Five low-bias cohorts narratively 20–88% higher ACM for the least regular — not a pooled HR.
All-cause mortalityC
1.53 vs the Median, Not the Quintile (Cribb 2023)
Same UK Biobank wave, a different pipeline and comparator: vs the median SRI, the 5th percentile (SRI=41) carried ACM HR 1.53 (1.41–1.66) and the 95th percentile (SRI=75) HR 0.90 (0.81–1.00). Non-linear, plateauing past the median — not the least-regular-quintile contrast the engine uses.
All-cause mortalityC
Self-Reported Irregularity, HR 1.30 (Omichi 2022)
J-MICC cohort of 81,382 adults, mean follow-up 9.1 years, using self-reported sleep/wake regularity rather than an accelerometer SRI — closer to what a user might report than Windred’s device-measured metric. Irregular vs regular sleepers carried ACM HR 1.30 (1.18–1.44), independent of sleep duration.
All-cause mortalityC
Regular-and-Sufficient vs Irregular-and-Short, HR 0.61 (Chung 2023)
MESA Sleep actigraphy cohort of 1,759 adults, median 7.0 years, 176 deaths: a “regular-optimal” sleep cluster (7.0±1.0 h, regular timing) carried ACM HR 0.61 (0.45–0.83) versus an “irregular-insufficient” cluster (5.8±1.4 h, roughly twice the irregularity) — a combined duration-and-regularity contrast, not a pure SRI-quintile comparison.

What argues against this

Cribb et al. 2023 reanalyzed the same UK Biobank wave with a different SRI pipeline and a different comparator (vs the median SRI, not the least-regular quintile): the 5th-percentile-vs-median contrast produced a similarly large HR (1.53), but the relationship plateaued past the median, with the 95th percentile reaching only HR 0.90 (0.81–1.00) — a much flatter payoff for above-median regularity than Windred's quintile contrast implies. This challenges the shape and generalizability of the engine's 0.70 figure without reversing the direction of the association.

Last reviewed 2 September 2026

Evidence

  1. Windred et al. (2024) — Sleep
    Sleep regularity is a stronger predictor of mortality risk than sleep duration: A prospective cohort study
    View source
  2. Kalkanis et al. (2025) — Sleep Medicine Reviews
    Sleep regularity as an important component of sleep hygiene: a systematic review
    View source
  3. Cribb et al. (2023) — eLife
    Sleep regularity and mortality: a prospective analysis in the UK Biobank
    View source
  4. Omichi et al. (2022) — Sleep Health
    Irregular sleep and all-cause mortality: A large prospective cohort study
    View source
  5. Chung et al. (2023) — Journal of Sleep Research
    Objectively regular sleep patterns and mortality in a prospective cohort: The Multi-Ethnic Study of Atherosclerosis
    View source
See how sleep regularity fits your full score
See how it fits the 8-metric index in the calculator.
Open calculator

Educational content only — not medical advice, diagnosis, or treatment. Not a medical device; not FDA evaluated. Consult a qualified healthcare professional about your own health, and call emergency services for urgent symptoms. Full medical disclaimer →