SleepShred
Get the app

Regularity & circadian: what the research actually says

Going to bed and waking at consistent times predicts mortality better than total duration — and social jet lag is the version of this most people live with.

All studies · 4

Sleep regularity is a stronger predictor of mortality risk than sleep duration: a prospective cohort studyWindred DP, Burns AC, Lane JM, et al. · Sleep 47(1):zsad253 · 2024In ~60,000 UK Biobank participants, how regular sleep was predicted mortality better than how long it was.Irregular sleep/wake patterns are associated with poorer academic performance and delayed circadian and sleep/wake timingPhillips AJK, Clerx WM, O'Brien CS, et al. · Scientific Reports 7:3216 · 2017Irregular sleepers had delayed melatonin onset and worse outcomes even at equal total sleep.Social jetlag and obesityRoenneberg T, Allebrandt KV, Merrow M, Vetter C · Current Biology 22(10):939–943 · 2012Each hour of social jet lag was associated with ~33% higher odds of being overweight.Social jetlag: misalignment of biological and social timeWittmann M, Dinich J, Merrow M, Roenneberg T · Chronobiology International 23(1–2):497–509 · 2006Defines social jet lag — the shift in sleep midpoint between work and free days — and links it to evening chronotypes and stimulant use.

Related guides

Sleep and fat lossRegularity beats duration

Related topics

Sleep duration & healthSleep apneaInsomnia, RLS & instrumentsWearables & trackingSleep, appetite & fat lossCaffeineAlcoholScreens & evening arousalLightSoundTemperature & airMeal timing & dietExercise, RHR & energySupplements & melatoninPartner, travel & environmentLife stages

Frequently asked questions

What does the research say about regularity & circadian?

In ~60,000 UK Biobank participants, how regular sleep was predicted mortality better than how long it was.

How do I track regularity & circadian?

SleepShred logs it in about 20 seconds a day and then compares your nights with and without it, so you see the effect on your own sleep instead of the study average.

Is SleepShred free?

No. SleepShred Pro is $4.99 per month or $29.99 per year, with no free trial and no ads. Everything stays on your iPhone.

Track it, don't guess it

SleepShred turns this research into a 20-second daily habit: log your night, see which of your own behaviours move your sleep, and screen for the disorders nobody diagnoses.

Get SleepShred for iPhone

Educational summary of published research, not medical advice. Screening scores are not diagnoses. If a score is elevated or you feel unwell, talk to a clinician.