Light exposure quick rules
Simple guidelines for using light to adjust your body clock faster.
The core principle
Bright light in the morning advances your body clock (makes you sleepy earlier). Bright light in the evening delays it (makes you sleepy later). The timing relative to your current body clock — not the local clock — is what matters.
Eastward travel (advancing the clock)
Get bright light exposure for 2–3 hours starting at your target wake time. Outdoor sunlight is ideal. If indoors, sit near a bright window.
Dim lights and avoid screens 2–3 hours before your target bedtime. Wear sunglasses if you must be outside in the evening.
Westward travel (delaying the clock)
Get bright light exposure in the late afternoon and early evening. This helps delay your body clock to match the later local time.
If you wake very early (before your target wake time), keep lights dim. Wear sunglasses if going outside at dawn.
Practical tips
- Outdoor sunlight is significantly brighter than indoor lighting — even overcast days provide useful light
- Blue-enriched light (sunlight, daylight-spectrum bulbs) is most effective
- Sunglasses are a useful tool for blocking light at the wrong times
- Shift your light timing by 1–1.5 hours each day as your body adjusts
- Consistency matters more than intensity — regular daily exposure beats one long session
This is general wellness guidance based on circadian rhythm research. It is not medical advice. Consult a healthcare professional for personal health concerns.