What it’s for
- Keeping a consistent body-clock signal
Spending time outdoors in morning daylight to help set the sleep-wake rhythm.
Purpose, evidence and practical considerations.
Natural light is an important circadian cue. Required exposure varies with brightness, season and individual timing, so evidence does not support a universal number of minutes.
Confidence: strong
Do not stare at the sun or any painfully bright source. Protect skin from burning during longer outdoor exposure. People with retinal disease, photosensitivity or medicines that increase light sensitivity should seek clinical guidance.
Morning light reaches retinal circadian photoreceptors and helps align the central body clock, generally advancing circadian timing and supporting earlier sleep-wake timing. Outdoor light is usually brighter than ordinary indoor light.
The evidence on this page does not automatically apply to:
How people use it, with their schedules, context and original sources.
10–20 min · each morning · within 60 min of waking
Session and schedule patterns reported in public protocols; these are observations, not instructions. Private and hidden usage is excluded.
These share a protocol with this intervention. This does not establish that they work together or are suitable alternatives.