Sleep Cycles Per Night Calculator

Enter how many hours you sleep to count your full 90-minute sleep cycles.

How to use

  1. Enter your values in the fields above.
  2. Press Calculate to see your result instantly.
  3. Use the Share button to copy a link to your result.

About this calculator

Sleep progresses through repeating cycles of roughly 90 minutes each, moving through light sleep, deep sleep, and REM before starting over. Waking up mid-cycle, especially during deep sleep, tends to leave people feeling groggy, while waking near the end of a cycle — closer to light sleep — usually feels much more refreshing.

This calculator divides your total sleep time by 90 minutes to show how many full cycles fit into the night and how many leftover minutes spill into a partial cycle. It's the same logic behind popular "sleep calculator" apps that suggest bedtimes or wake times timed to land at a cycle boundary rather than in the middle of deep sleep.

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