Sleep Onset
clock time
The clock timestamp at which sleep was first detected.
Typical optimal range 9:30 PM - 11:30 PM
Population median 11:45 PM
Key factors
- Shift work and rotating schedules
- Evening light exposure
- Social and work obligations
What affects this metric
- Morning light exposure pulls onset earlier.
- Late or long naps push onset later.
- Melatonin timing shifts onset more than melatonin dose does.
- Evening bright light and screens delay sleep onset.
- Caffeine after early afternoon shifts onset later.
- Weekend schedule shifts move onset and take days to reset.
References
Peer-reviewed sources supporting the key factors, contributing factors, and typical optimal range shown above.
- Duffy JF, Czeisler CA. Effect of light on human circadian physiology. Sleep Medicine Clinics. 2009;4(2):165–177. doi.org/10.1016/j.jsmc.2009.01.004
- Roenneberg T, Kuehnle T, Juda M, et al.. Epidemiology of the human circadian clock. Sleep Medicine Reviews. 2007;11(6):429–438. doi.org/10.1016/j.smrv.2007.07.005
- Drake C, Roehrs T, Shambroom J, Roth T. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. Journal of Clinical Sleep Medicine. 2013;9(11):1195–1200. doi.org/10.5664/jcsm.3170
- Dhand R, Sohal H. Good sleep, bad sleep! The role of daytime naps in healthy adults. Current Opinion in Pulmonary Medicine. 2006;12(6):379–382. doi.org/10.1097/01.mcp.0000245703.92311.d0
This guide is general information, not medical advice. Talk to your clinician about your own results.