🌙 Sleep Cycle Calculator
Wake up feeling refreshed by timing your sleep to complete 90-minute cycles. Science-backed, completely free.
How Sleep Cycles Work
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90-Minute Cycles
Each sleep cycle lasts about 90 minutes, moving through light sleep, deep sleep, and REM.
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Complete Cycles
Waking between cycles causes grogginess. Waking at the end of a cycle helps you feel refreshed.
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4-6 Cycles
Adults need 4-6 complete cycles (6-9 hours) per night. 5 cycles (7.5h) is optimal for most people.