Circadian Light Protocol
Satchin Panda's circadian light protocol pairs bright light early in the day with dim, warm light at night to keep your body clock on schedule. Morning daylight suppresses lingering melatonin and sharpens alertness, while evening screens and bright bulbs suppress the melatonin you need for sleep, making this one of the cheapest, highest-yield circadian levers available.
Panda is best known for time-restricted eating, but he is just as emphatic that light sets your clock. Bright light in the first half of the day anchors your rhythm, sharpens alertness and primes good melatonin release at night; bright light and screens in the evening do the opposite, suppressing melatonin and pushing your clock later. The fix is simple and mostly free: chase daylight early, dim and warm your light in the evening, and reclaim darkness for sleep. He notes ordinary indoor light is too dim to count as 'day' and too bright to count as 'night'.
Why it works▼
Get bright daylight in the first half of the day
Morning light anchors the clock, boosts daytime alertness and sets up melatonin at night.
Don't let daytime be dim
Dim daytime light fails to fully anchor the clock and can leave you sleepy.
Lower and warm your light a few hours before bed
Evening blue light suppresses the melatonin rise you need to fall asleep.
Keep the bedroom dark for sleep
Panda's line: in modern life we have 'lost our right to darkness', and night light disrupts metabolism and sleep.
Get blue light by day without frying your eyes
You want enough daytime blue light to set the clock while still protecting your eyes.
Keep light and sleep timing regular
Consistency keeps the clock stable; erratic light and timing desynchronise it.
- Anyone who sleeps poorly or wakes groggy
- Indoor and desk-bound workers
- Shift workers and travelers
- People optimising energy and circadian health
- Light is one lever; pair it with consistent sleep timing and sensible meal timing for full effect
- Bright-light exposure can affect people with bipolar disorder or some eye conditions; if that applies, check with a clinician before using bright lamps
- Never look directly at the sun to 'get light'; sensible outdoor exposure is enough
- Shift workers face a genuinely hard problem and may need a tailored plan
- Educational only, not medical advice
- July 3, 2026 Protocol published.
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Not medical advice. This page is for education only and is not a substitute for professional medical care. Consult a qualified clinician before changing your health routine.
Independent curation. YourProtocol.ai is an independent platform. This protocol is based on the publicly available work of Satchin Panda and is not created, reviewed, endorsed by, or affiliated with Satchin Panda or Salk Institute.