SleepShred
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 · Current Biology 23(16):1554–1558 · 2013
Key finding
A week of camping without electric light shifted the internal clock ~2 h earlier and aligned it to sunrise/sunset.
Citation
Related guides
Related studies
The new world atlas of artificial night sky brightness80% of the world and 99% of US/European populations live under light-polluted skies — the 'world is physically brighter'.Artificially lit surface of Earth at night increasing in radiance and extentSatellite data: outdoor lit area and brightness grew ~2%/year 2012–2016.Day and night light exposure are associated with psychiatric disordersBrighter days and darker nights were each independently linked to lower risk of depression and other disorders — daytime light offsets night light.Effects of light on human circadian rhythms, sleep and moodAccessible review of how timing, intensity and spectrum of light set the clock and affect sleep.Exposure to room light before bedtime suppresses melatonin onset and shortens…Ordinary room light in the hours before bed suppressed melatonin in 99% of people and shortened its duration ~90 min.
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 iPhoneEducational 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.