How many cycles is a full night?

Five cycles is 7.5 hours of sleep, six is 9 — the range covering most adults' needs. Four cycles (6 hours) works as a floor, not a habit.

Are cycles exactly 90 minutes?

They average 90 but range 80–110 minutes and lengthen through the night. Treat the suggested times as good targets, not precision medicine.

Sleep Cycle Calculator

Wake times that respect your 90-minute cycles.

Bedtime

3:45 AM

3 cycles · 4.5 h sleep (minimum)

5:15 AM

4 cycles · 6.0 h sleep

6:45 AMSweet spot

5 cycles · 7.5 h sleep

8:15 AM

6 cycles · 9.0 h sleep

Assumes ~15 minutes to fall asleep and 90-minute cycles. Wake at one of these times to surface between cycles.

Sleep runs in roughly 90-minute cycles, and waking at a cycle boundary tends to feel better than waking mid-cycle. Enter your bedtime to see wake times that land between cycles — or work backwards from an alarm to a bedtime — with an average 15 minutes to fall asleep included.

How to use it

1.Choose bedtime → wake times, or alarm → bedtimes.
2.Enter the time.
3.Pick the option closest to your target sleep length (5–6 cycles is typical).

Questions people ask

How many cycles is a full night?: Five cycles is 7.5 hours of sleep, six is 9 — the range covering most adults' needs. Four cycles (6 hours) works as a floor, not a habit.
Are cycles exactly 90 minutes?: They average 90 but range 80–110 minutes and lengthen through the night. Treat the suggested times as good targets, not precision medicine.

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