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Sleep Cycle Calculator
Plan your sleep around 90-minute cycles so you wake at the end of a light-sleep phase — refreshed instead of groggy. Enter your target wake time or bed time below.
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About sleep cycles: A full sleep cycle lasts ~90 minutes and alternates between light sleep, deep sleep, and REM. Waking at the end of a cycle (during light sleep) leaves you feeling more refreshed than waking during deep sleep. Aim for 4–6 cycles (6–9 hours) per night. Adults typically need 7–9 hours.
How it works
- Each sleep cycle lasts 90 minutes. Count backward from your target time in 90-minute increments.
- Add a fall-asleep buffer (default 15 min) to account for the time it takes to actually fall asleep after going to bed.
- The schedule shows options from 3 cycles (4.5 h) to 8 cycles (12 h). Fewer than 4 cycles is not recommended for most adults.
- The highlighted rows (4–6 cycles) represent the recommended range for most adults.