Why is morning sunlight important?

Morning sunlight helps set your circadian rhythms, increase daytime alertness, and support sleep and mood. 1

• Sunlight soon after waking: Bright light in the first 30–60 minutes helps time the morning cortisol peak, which supports the brain and body’s wake-up signal. 2
• Melatonin and sleep timing: Morning light suppresses lingering melatonin and starts a timer that helps you fall asleep about 16 hours later. 3
• Late-afternoon and evening sunlight: Light around sunset can help protect circadian mechanisms from the disruptive effects of light later at night. 4
• Outdoor light matters: Artificial light and phone screens generally do not provide enough light to replace morning sunlight; light through a window or windshield is much less effective than getting outside. 5