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Does morning sunlight reset your body clock and improve sleep?
Morning light shifts the body clock and modestly helps sleep problems; less clear for good sleepers.
What you hear: “Getting sunlight in your eyes soon after waking resets your body clock and helps you sleep better at night.”
What the studies found
A review of 53 studies (1,154 people with sleep problems) found bright light therapy helped sleep, with small to medium effects. A 2023 review of insomnia trials found light cut time awake during the night by about 11 minutes measured by wrist devices, and morning light moved sleep earlier. In 88,905 UK adults wearing light sensors, the brightest days went with a 17 to 34% lower death rate, but that is a link only.
What you could do
Getting outside in daylight in the morning is free and low risk; never stare at the sun itself.
See it in the habit library, with what it means for your own longevity score.
Not medical advice. General information from published studies, not a diagnosis or a treatment plan. Talk with your doctor before starting a supplement or changing a medicine, especially if you are pregnant, take other medicines or have a health condition.
How we judged it
Partly true: Some truth, but oversold as usually said. We judge the claim as it is usually said online, not the habit itself. Trials assign people at random, so they can show cause; observed studies follow people and show a link, not proof. Last checked: October 2026.
The studies, in their own words
- van Maanen et al. Sleep Med Rev 2016
light therapy is effective for sleep problems in general, particularly for circadian outcomes and insomnia symptoms. However, most effect sizes are small to medium.
- Chambe et al. J Sleep Res 2023
Morning light exposure advanced sleep-wake rhythms and evening exposure led to a delay.
- Windred et al. Proc Natl Acad Sci USA 2024
Individuals with brighter day light had incrementally lower all-cause mortality risk (adjusted-HR ranges: 0.84 to 0.90 [50 to 70th light exposure percentiles], 0.74 to 0.84 [70 to 90th], and 0.66 to 0.83 [90 to 100th])
More claims, checked
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- Not provenCold plunges and ice baths
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