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Sleep Calculator

I need to wake up at

Hour

Minute

AM/PM

How Sleep Cycles Work

Cycle 1Cycle 2Cycle 3Cycle 4Cycle 5Cycle 6

Light

Deep

REM

Set your wake-up time and click Calculate to see optimal bedtimes

How This Works

Sleep occurs in cycles of approximately 90 minutes, each progressing through light sleep (N1, N2), deep sleep (N3), and REM sleep. Waking between cycles rather than in the middle of one helps you feel more refreshed. Most adults need 5-6 complete cycles (7.5-9 hours) per night. The calculator adds 15 minutes to account for the average time it takes to fall asleep. Deep sleep is most abundant in early cycles, while REM sleep increases in later cycles, making both short and long sleep suboptimal for cognitive function.

This tool is for educational purposes only. Not medical advice. Consult a healthcare professional.