Why is morning sunlight important?

Morning sunlight is important because it promotes wakefulness, helps set your circadian rhythms, and starts a timer that supports falling asleep about 16 hours later. 1

• It suppresses melatonin and supports the morning cortisol rise: Light helps suppress melatonin lingering around after waking and helps time cortisol early in the day, supporting alertness. 2
• It supports biological rhythms and metabolism, and may benefit mood: Morning light helps set brain-and-body rhythms and proper metabolism; Huberman also links it with benefits for mood and mental health. 3
• Intensity and duration both matter: Brighter light can require less exposure, while dim or overcast conditions call for staying outside longer. If you miss a day, the guidance is to double the next day's exposure duration. 4 5