Sleep Cycle & Bedtime Calculator

Sleep runs in roughly 90-minute cycles. Waking up at the end of a cycle usually feels much easier than being woken mid-cycle. Use this calculator to find bedtimes or wake-up times that line up with full cycles.

How it works: Each sleep cycle lasts about 90 minutes and moves through light sleep, deep sleep, and REM sleep. This calculator counts backwards or forwards in 90-minute steps and adds roughly 15 minutes for falling asleep. Real sleep varies from night to night, so treat the results as a helpful guide, not a strict schedule.

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