Sleep
Phase Response Curve
How timed light, melatonin, and exercise shift your body clock earlier or later—why morning sun and late screens have opposite effects.
The phase response curve describes how light, melatonin, and exercise at specific circadian times shift your internal clock earlier or later. Morning bright light generally advances rhythm; late evening light delays it.
Mis-timed interventions explain why late workouts or screens push bedtime.
Common questions
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When should you get bright light to shift earlier?
Soon after your desired wake time is the usual advance window. Consistency for several days beats one intense session.
Related terms
Put Phase Response Curve into practice
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