Sleep Cycle Calculator

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Sleep Cycle Calculator

Pick a wake time (or bed time) and find the matching 90-minute cycle slots

Calculate the best time to sleep or wake up based on 90-minute sleep cycles.

Recommended bedtimes

6 cycles (9h) --:--
5 cycles (7.5h) --:--
4 cycles (6h) --:--
3 cycles (4.5h) --:--

What is a sleep cycle?

A sleep cycle is one full pass through the four sleep stages: light sleep, deep sleep, REM, and a brief waking moment. The popular 90-minute model says each cycle lasts about 90 minutes, so timing your alarm to the end of a cycle (rather than the middle) helps you wake up feeling more refreshed. Add your personal fall-asleep latency on top, and aim for 5 cycles (7.5h) for the best balance of rest and recovery.

This tool uses the popular 90-minute cycle model. Real sleep cycles vary between 70 and 110 minutes depending on age, sleep stage, and individual biology. For chronic sleep issues, please consult a doctor.

See also: Time Zone Converter, Cron Generator

Sleep Cycle Calculator

Calculate optimal bed and wake times based on 90-minute sleep cycles. All local, no upload.

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