Sleep Calculator
Plan bedtime or wake time using approximate 90-minute sleep-cycle intervals.
Suggested bedtime
21:45
for about 9 hours (6 × 90-minute cycles)
6 cycles (9 h)21:45
5 cycles (7.5 h)23:15
4 cycles (6 h)00:45
Sleep cycles vary between people and through the night; cycle timing is only a rough planning aid. Adults generally need 7 or more hours of sleep.
About the Sleep Calculator
Plan bedtime or wake time using approximate 90-minute sleep-cycle intervals.
It runs entirely in your browser — nothing you type is sent to a server — and the result updates as you edit the inputs. Estimates are for educational and informational purposes only; see ourdisclaimer.
Common searches
- sleep cycles
- bedtime
- wake up
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