Sleep calculator: when to go to bed or wake up

How the sleep calculator works

Sleep runs in cycles of light sleep, deep sleep and dream sleep. One cycle lasts about 90 minutes on average, and most nights have four to six of them. Waking up at the end of a cycle often feels easier than being pulled out of the middle of one.

The calculator counts back or forward in steps of 90 minutes and adds 15 minutes for falling asleep. The result is an estimate: cycles vary from person to person and from night to night, usually between about 70 and 110 minutes.

How much sleep do you need?

Most adults do well with seven to nine hours of sleep, which is five to six cycles. Teenagers and children need more. The number is a guide, not a target: how rested you feel during the day tells you more than the clock.

Regular times help more than a perfect calculation. Going to bed and getting up at similar times, also on weekends, makes falling asleep easier for many people.

Ideas for a calmer evening

• Dim the lights and put screens away about 30 minutes before the time you picked.
• Keep the room cool, dark and quiet, or play a soft steady sound at low volume.
• Try a few minutes of slow breathing with a longer exhale.
• Avoid heavy meals and caffeine late in the day.
• If you cannot sleep, get up for a short while instead of watching the clock.

The sleep calculator gives general estimates, not medical advice. If you have lasting sleep problems, talk to a doctor.

Wind down with Taceora

Taceora is a meditation app with brown noise and other sounds with a sleep timer, four breathing exercises and meditations from 3 minutes. It works offline, without an account and without ads.