Sleep Calculator
Wake up between sleep cycles instead of in the middle of one. Enter when you need to get up — or when you are going to bed — and get the best times.
How it works
- 1
Choose what you know
The time you must wake up, or the time you are going to bed.
- 2
Set how long you take to fall asleep
Most people need around 15 minutes.
- 3
Pick a time
Suggestions for 6, 5 and 4 full sleep cycles.
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Frequently asked questions
About 90 minutes on average, though it can range from roughly 80 to 110 minutes.
Why sleep cycles matter
During the night the brain moves through cycles of light sleep, deep sleep and REM sleep that last about 90 minutes each. Waking at the end of a cycle usually feels easier than being pulled out of deep sleep, which causes grogginess.
Five or six cycles (7.5 to 9 hours) match the 7–9 hours adults are advised to sleep. Cycle length varies from person to person, so treat the times as a helpful starting point.