Sleep Cycle Calculator
Find bedtimes for your wake-up time, or wake-up times if you sleep now, using 90-minute cycles plus time to fall asleep. A general guide, not medical advice.
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How to use
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Choose whether your wake-up time is fixed or you’re going to sleep soon
Enter the time and how long you take to fall asleep
Check the times that fit 4, 5 or 6 cycles
How it works and good to know
Uses the common rule of thumb that sleep repeats in cycles of about 90 minutes. The time to fall asleep (default 15 minutes, 0–90) is added or subtracted to show times that fit 4, 5 or 6 cycles. Real cycles vary from 70 to 120 minutes between people and nights, so treat this as a guide, not medical advice.