Sleep Cycle Calculator
Find the best times to fall asleep or wake up based on 90-minute sleep cycles. Waking between cycles helps you feel refreshed instead of groggy.
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Recommended Times
💤 Each sleep cycle is ~90 minutes. It takes ~15 min to fall asleep. Aim for 5–6 complete cycles (7.5–9 hours).
😴 Sleep Cycles
How sleep works
- Each cycle (~90 min) has stages: light sleep → deep sleep → REM.
- Waking during deep sleep causes grogginess.
- Waking at the end of a cycle (between cycles) helps you feel alert.
🎯 Recommendations
How much sleep?
- Adults (18–64): 7–9 hours (5–6 cycles)
- Teens (14–17): 8–10 hours
- Elderly (65+): 7–8 hours
- Quality matters more than quantity