Sleep Cycle Calculator
Wake up between sleep cycles and feel more refreshed.
How to use: Choose whether you know your wake-up time or bedtime (or are going to bed now), enter the time, and pick one of the suggested times.
How to use the Sleep Cycle Calculator
Sleep happens in cycles that last roughly 90 minutes, moving from light sleep to deep sleep and dreaming REM sleep. Waking up at the end of a cycle, when sleep is lightest, usually feels much easier than being dragged out of deep sleep by an alarm, even if the total time asleep is similar.
If you have to be up at a certain time, choose “Wake up at a set time” and enter it. The calculator counts back in 90-minute cycles and adds the time it usually takes you to fall asleep, giving bedtimes for three to six cycles. If you know when you will go to bed, choose that option instead to get alarm times, or press “Go to bed now” for times based on the current clock.
Five or six cycles, about 7.5 to 9 hours, are highlighted as recommended, matching health guidance that most adults need seven to nine hours a night. Teenagers need more. Adjust the minutes to fall asleep if you usually drift off quickly or take a while.
Cycle length varies between people and through the night, so treat the times as a helpful guide and notice how you feel. A regular schedule, a dark, cool room and less screen time before bed help most. This tool gives general information, not medical advice.
Frequently asked questions
How long is a sleep cycle?
About 90 minutes on average, though it varies from roughly 70 to 120 minutes between people and through the night.
How many cycles do I need?
Most adults feel best with five or six cycles, about 7.5 to 9 hours of sleep.
Why add time to fall asleep?
Cycles start when you actually fall asleep, not when you get into bed. The average adult needs 10 to 20 minutes.