# Regularity beats duration

In 60,000 people, sleep regularity predicted mortality better than sleep length.



## Takeaways

- Same wake time 7 days a week.

- Morning light anchors it.

- Weekend lie-ins are a time-zone flight.



Galpin's practical fix for most circadian issues is a consistent wake time and morning light. The data back it: in the UK Biobank, regularity of sleep timing outperformed duration as a predictor of mortality; irregular sleepers had delayed melatonin onset and worse performance at equal total sleep; and each hour of weekday–weekend 'social jet lag' adds ~33% odds of overweight.

Trends shows your midpoint variability and social jet lag; the Signals card flags it when it's high.



## Sources

- 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)

- 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)

- Social jetlag: misalignment of biological and social time (Wittmann M, Dinich J, Merrow M, Roenneberg T, 2006)

- Social jetlag and obesity (Roenneberg T, Allebrandt KV, Merrow M, Vetter C, 2012)

- Entrainment of the human circadian clock to the natural light-dark cycle (Wright KP Jr, McHill AW, Birks BR, Griffin BR, Rusterholz T, Chinoy ED, 2013)

---
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.

SleepShred for iPhone: https://apps.apple.com/app/id6802040541