Sleep Cycle Calculator
Find the optimal times to go to sleep or wake up based on 90-minute REM cycles.
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You should try to fall asleep at one of these times:
Optimal
9:45
PM
6 Cycles
9 Hours Sleep
Optimal
11:15
PM
5 Cycles
7.5 Hours Sleep
12:45
AM
4 Cycles
6 Hours Sleep
2:15
AM
3 Cycles
4.5 Hours Sleep
Note: A standard sleep cycle consists of NREM and REM stages and lasts exactly 90 minutes. Waking up during a REM cycle (mid-cycle) makes you feel exhausted.