# 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

- **Sleep regularity is a stronger predictor of mortality risk than sleep duration: a prospective cohort study** — Windred DP, Burns AC, Lane JM, et al. (2024), Sleep 47(1):zsad253. In ~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 timing** — Phillips AJK, Clerx WM, O'Brien CS, et al. (2017), Scientific Reports 7:3216. Irregular sleepers had delayed melatonin onset and worse outcomes even at equal total sleep.

- **Social jetlag and obesity** — Roenneberg T, Allebrandt KV, Merrow M, Vetter C (2012), Current Biology 22(10):939–943. Each hour of social jet lag was associated with ~33% higher odds of being overweight.

- **Social jetlag: misalignment of biological and social time** — Wittmann M, Dinich J, Merrow M, Roenneberg T (2006), Chronobiology International 23(1–2):497–509. Defines social jet lag — the shift in sleep midpoint between work and free days — and links it to evening chronotypes and stimulant use.

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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.

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