Sleep Cycle Calculator

Wake up at the end of a full 90-minute sleep cycle for better rest. Choose your wake time and either number of cycles or desired sleep length.

Wake-up time

By number of cyclesBy desired sleep length

Number of 90-min cycles (3–8)

Best bedtime for your selection

21:15

6 cycles → 9 h (540 min) of sleep • wake 06:30

All good bedtimes (allowing ~15 min to fall asleep)

3 cycles (4.5 h): 01:45
4 cycles (6 h): 00:15
5 cycles (7.5 h)Recommended: 22:45
6 cycles (9 h)Recommended: 21:15
7 cycles (10.5 h): 19:45
8 cycles (12 h): 18:15

5 cycles ≈ 7 h 30 m • 6 cycles ≈ 9 h. Most adults feel best after 5 or 6 full cycles. Going to bed at the wrong phase can leave you groggy even after “enough” hours.