Sleep Calculator
Waking up groggy? Sleep moves in ~90-minute cycles — wake at the end of one and you feel refreshed. Enter your alarm time to see the best bedtimes.
😴 Two modes
Pick the mode that fits: set an alarm, or fall asleep right now.
Result
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How this sleep calculator works
One sleep cycle lasts roughly 90 minutes and ends with lighter sleep — waking mid-cycle (deep sleep) is what makes alarms feel brutal. The calculator counts back 6, 5, 4 and 3 cycles from your alarm and adds ~15 minutes for the average time it takes to fall asleep. Six cycles (9 hours) is ideal; three (4½ hours) is a short night, not a habit.
Common uses
- Pick a bedtime before an early flight or exam morning.
- Decide whether a late-night nap is worth it — see what a 3-cycle night means.
- Shift workers planning sleep around rotating alarms.
For general wellness only — not medical advice. Cycle length varies between 80–100 minutes per person.
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