Sleep Cycle Calculator
Calculate ideal sleep or wake times based on 90-minute sleep cycles. Waking at the end of a cycle (not in the middle) leaves you feeling more refreshed.
Inputs
Recommended times
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Best (5 cycles)
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Ideal duration for adults
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About Sleep Cycle Calculator
Sleep cycles
A full cycle averages ~90 minutes and progresses through light sleep → deep sleep → REM. Waking at the END of a cycle (vs being woken mid-deep-sleep) leaves you less groggy.
15-min fall-asleep buffer
Most people take 10-20 minutes to fall asleep. The calculator adds 15 minutes to the chosen bedtime. If you fall asleep instantly, use times 15 minutes later; if you take longer, earlier.
Caveats
Cycle length varies 80-110 min by person and over the night. This is a rough guide — not strict science. Consistent bedtime/waketime matters more than micro-optimizing the wake moment.