About this tool
This sleep cycle calculator helps you plan bedtime around 90-minute sleep cycles.
Many people move through lighter and deeper sleep in repeating waves of roughly ninety minutes, and waking up near the end of a wave often feels easier than waking up in the middle of one.
Choose the time you need to get up and the tool counts backwards in 90-minute steps, adding about 15 minutes for falling asleep, to suggest bedtimes for 6, 5, 4 or 3 cycles.
Or tap Sleep now to see when to set an alarm if you lie down at this moment. For example, waking at 07:00 points to 21:45 for six cycles, or 23:15 for five.
The 90-minute cycle is only an average tendency, and it varies from person to person and from night to night.
Teens generally feel best with around 8 to 10 hours of sleep, so six cycles (9 hours) fits that range when your schedule allows.
If sleeping stays difficult for you, talk with a parent, guardian or a healthcare professional. Everything is calculated in your browser, and nothing is saved or sent anywhere.
ⓘ This is not medical advice.
How to use
- Choose the time you need to wake up.
- Pick a suggested bedtime. Each one shows how many 90-minute cycles and hours of sleep it gives.
- Or open the Sleep now tab and tap the button to see wake-up times if you fall asleep right now.
- Use the share button to send the times to a friend.