Sleep Cycle Calculator

Sleep happens in roughly 90-minute cycles of light, deep, and REM stages. Waking at the end of a cycle (in light sleep) usually feels far more refreshing than waking mid-cycle, even with the same total hours. Enter the time you need to wake up to get suggested bedtimes, or enter when you'll fall asleep to get suggested wake-up times. The 14-minute average time it takes to fall asleep is folded in automatically.

1. Pick a direction with the toggle: solve for bedtime, or solve for wake-up time.
2. Type the reference time. The 4-, 5-, and 6-cycle options update instantly.
3. Most adults aim for 5–6 cycles (~7.5–9 hours). Pick the option that fits your schedule.

• Why 90-minute cycles?

  An adult sleep cycle averages about 90 minutes — light sleep, then deep sleep, then REM. Waking just after a cycle ends, while you're back in light sleep, is reported to feel far more refreshing than waking mid-cycle.

• Where does the “14 minutes to fall asleep” come from?

  Healthy adults take 10–20 minutes on average to fall asleep after lying down. 14 minutes is a common midpoint estimate. If you typically take more or less, adjust the suggested times accordingly.

• Are cycles always exactly 90 minutes?

  No — they vary between roughly 80–110 minutes per person and per night. Treat this as a guide and tweak the suggestions against how you actually feel after a few nights.

• Does this work for naps?

  Not for short power naps (≤ 20 minutes). It's useful when you have time for one or more full cycles (≥ ~90 minutes).