Sleep Calculator

Find the best bedtimes based on 90-minute sleep cycles.

I want to wake up at

Go to bed at one of these times

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Times allow ~15 min to fall asleep. Aim for 5–6 cycles.

Why 90-minute cycles?

Sleep moves through cycles of roughly 90 minutes. Waking at the end of a cycle — rather than mid-cycle — tends to leave you feeling more refreshed. The calculator counts back 5 and 6 cycles (7.5 and 9 hours) from your wake time, plus time to fall asleep.