Sleep Cycle Calculator
Moderate evidence ↗Sleep cycle calculator: enter your wake-up time and get the best bedtimes based on 90-minute sleep cycles plus time to fall asleep. Free and instant.
Best times to fall asleep
9:45 PM
6 cycles · 9 h asleep · recommended
11:15 PM
5 cycles · 7.5 h asleep · recommended
12:45 AM
4 cycles · 6 h asleep
2:15 AM
3 cycles · 4.5 h asleep
Assumes ~90-minute sleep cycles plus 15 minutes to fall asleep. Cycles vary person to person (roughly 80–100 minutes) — treat these as good starting points, then adjust by how you feel on waking.
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