Sun & moon: light and your sleep
Choose your city or use your location to see today's sunrise, sunset, daylight length and current moon phase.
Why light matters for sleep
Your body clock (circadian rhythm) is set mainly by light. Morning sunlight tells your brain to stop producing melatonin and feel alert; as light fades in the evening, melatonin rises and prepares you for sleep. Getting bright light soon after sunrise and dimming lights after sunset helps you fall asleep faster and wake up more easily. The moon's brightness has a much smaller effect, but many people report lighter sleep around the full moon.
Frequently asked questions
How is sunrise and sunset calculated?
We use an astronomical formula based on your city's latitude and longitude and today's date, calculated directly in your browser.
Does the moon phase really affect sleep?
Some studies suggest slightly shorter, lighter sleep around the full moon, though the effect is small compared to artificial light exposure.
How can I use this to sleep better?
Try to get natural light within an hour of sunrise, and dim screens and bright lights in the hour before your target bedtime.
Want to go further?
Explore our guides and other calculators.