Sleep Cycle Calculator
Choose whether you want to set a wake-up time or a bedtime, and see the best matching times.
Go to bed at one of these times:
02:15
3 cycles · 4.5h
00:45
4 cycles · 6.0h
23:15
5 cycles · 7.5h
21:45
6 cycles · 9.0h
How sleep cycles work
Sleep happens in cycles of roughly 90 minutes, alternating between light sleep, deep sleep and REM. Waking up at the end of a cycle, rather than in the middle of deep sleep, generally feels more refreshing — this tool works backward or forward from your target time in 90-minute steps.
Frequently asked questions
Why 90-minute cycles?
A full sleep cycle — moving through light sleep, deep sleep and REM — takes about 90 minutes on average, and waking up between cycles rather than in the middle of one tends to feel less groggy.
Why add 15 minutes before bedtime suggestions?
Most people take a few minutes to actually fall asleep after lying down, so this tool adds a buffer to the calculation.
How many cycles should I aim for?
Five to six cycles (7.5 to 9 hours) is the typical recommendation for adults, though individual needs vary.
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