Sleep Cycle Calculator
Enter when you want to wake up, or say you're heading to bed right now, and this calculator suggests bedtimes or wake-up times timed to complete full 90-minute sleep cycles — so you're more likely to wake up feeling rested instead of groggy.
Suggested bedtimes
How it works
Sleep happens in cycles of roughly 90 minutes each, moving through light sleep, deep sleep, and REM. Waking up at the end of a cycle — rather than in the middle of one — tends to feel easier, so this tool counts whole cycles backward from your wake-up time (or forward from now) and adds about 14 minutes for the average time it takes to fall asleep.
Tip
Most adults do well with 5 to 6 cycles (7.5–9 hours) of sleep a night. If you can only fit in fewer cycles, waking at the end of one is still better than waking mid-cycle.
Is this exact?
Cycle length and the time it takes to fall asleep vary from person to person and night to night, so treat these times as a helpful starting point rather than an exact science. This is not medical advice — if you have ongoing sleep problems, talk to a doctor.
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