Sleep Cycle Calculator

Bedtimes and wake-up times based on 90-minute sleep cycles.

Wake-up time

Falling asleep (min)

Go to bed at

21:45

6 cycles · 9 of sleep

Optimal

23:15

5 cycles · 7.5 of sleep

Optimal

00:45

4 cycles · 6 of sleep

02:15

3 cycles · 4.5 of sleep

175 available

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About this calculator

Plan bedtimes and wake-ups around 90-minute sleep cycles, including time to fall asleep, with optimal 5–6 cycle options highlighted.

Why 90 minutes?

A full sleep cycle (light, deep, REM) averages about 90 minutes; waking at its end avoids grogginess.

How many cycles?

Most adults need 5–6 cycles (7.5–9 hours); the calculator marks these optimal.

Does fall-asleep time matter?

Yes — add your typical 10–20 minutes so cycles count from real sleep onset.