Why is morning sunlight important?

Morning sunlight helps set circadian rhythms, supporting alertness during the day and better sleep at night.

1. Signals daytime: Light entering the eyes activates pathways to the brain’s central clock, which coordinates signals across the body and helps set the timing of wakefulness and sleep. 1
2. Times the cortisol rise: Getting bright light early helps bring the daily cortisol peak closer to waking, supporting a timely wake-up signal. 2
3. Supports alertness: Morning light suppresses melatonin that may remain at waking and interacts with the adenosine system, helping reduce lingering sleepiness. 3
4. Shapes daily rhythms: Morning light affects mood, metabolism, and sleep timing, and starts a timer that helps prepare you to fall asleep about 16 hours later. 4
5. Outdoor light is stronger: Outdoor sunlight provides much more light than typical indoor lighting, including on cloudy days; aim to get morning light consistently, ideally on at least 80% of days. 5 6