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Sleep Cycle Calculator

Calculate optimal sleep and wake times based on 90-minute sleep cycles. Wake up refreshed by timing your sleep.

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Sleep Planner

Go to bed at...

9:45 PM

9 hours of sleep (6 cycles)

Recommended

11:15 PM

7.5 hours of sleep (5 cycles)

Recommended

12:45 AM

6 hours of sleep (4 cycles)

Sleep cycles last ~90 minutes. Waking at the end of a cycle helps you feel refreshed. Times include ~15 minutes to fall asleep.

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How to Use Sleep Cycle Calculator

  1. 1

    Choose mode

    Select whether you want to set a wake-up time or bedtime.

  2. 2

    Set time

    Enter your desired wake-up time or bedtime.

  3. 3

    View options

    See optimal times for 4, 5, and 6 complete sleep cycles.

  4. 4

    Choose recommended

    Aim for 5-6 cycles (7.5-9 hours) for optimal rest.

Frequently Asked Questions

A sleep cycle lasts approximately 90 minutes and includes stages of light sleep, deep sleep, and REM sleep. Waking at the end of a complete cycle (rather than mid-cycle) helps you feel more refreshed and alert.

Most adults need 5-6 complete cycles (7.5-9 hours). Some people function well on 4 cycles (6 hours), but this isn't recommended long-term. Quality of sleep matters as much as quantity.

The average person takes 10-20 minutes to fall asleep (sleep onset latency). We use 15 minutes as an average. If you consistently fall asleep much faster or slower, adjust accordingly.

Waking naturally at the end of a sleep cycle is ideal. If you must use an alarm, try placing it at the end of a cycle. Consistent sleep and wake times help regulate your circadian rhythm.