RapidCheck

Sleep Cycle Calculator

Find the best bedtime or wake-up time using 90-minute sleep cycles.

Last updated: 21 Aug 2026

Quick answer

Sleep runs in ~90-minute cycles; waking at the end of a cycle feels more refreshed. Enter the time you want to wake up and this tool suggests bedtimes for 5–6 complete cycles (7.5–9 hours), allowing ~15 minutes to fall asleep.

Sleep happens in ~90-minute cycles, and waking at the end of a cycle feels more refreshed than mid-cycle. Enter your wake-up time to get bedtimes for 5–6 full cycles (plus ~15 minutes to fall asleep).

How to use sleep cycles

  1. 1 Enter the time you need to wake up.
  2. 2 We count back 5 and 6 sleep cycles (90 minutes each) plus 15 minutes to fall asleep.
  3. 3 Pick one of the suggested bedtimes.

Frequently asked questions

How long is a sleep cycle?
About 90 minutes; a full night is typically 5–6 cycles (7.5–9 hours).
Why wake at the end of a cycle?
Waking during deep sleep causes grogginess; waking at a cycle end (lighter sleep) feels more refreshed.
Why add 15 minutes?
Most people take around 15 minutes to fall asleep, so we add that to the bedtime.

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