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Sleep Cycle Calculator
Optimal wake times based on sleep cycles
Runs locally in your browser
Parameters
Results
- Recommended wake times
- 05:15, 06:45, 08:15
- 4 cycles (6 hr)
- 05:15
- 5 cycles (7.5 hr)
- 06:45
- 6 cycles (9 hr)
- 08:15
1 sleep cycle ≈ 90 minutes.
How it works
Suggests wake-up times aligned with 90-minute sleep cycles to reduce grogginess.
Who it's for: Shift workers, students, and anyone optimizing alarm times for lighter sleep-stage awakening.
Models sleep in ~90-minute cycles from bedtime plus fall-asleep latency.
Shows recommended wake times after 4, 5, and 6 complete cycles.
Displays both a summary list and individual cycle wake times.
How to use
- Enter Bedtime hour in 24-hour format (23 = 11:00 PM).
- Enter Time to fall asleep in minutes — most adults need 10–20 minutes.
- Review Recommended wake times — choose the option that fits your schedule.
- Prefer 5 or 6 cycles (7.5–9 hours in bed) for adequate rest per CDC adult guidelines.
- Set your alarm to one of the listed times rather than mid-cycle.
- Maintain consistent bed and wake times even on weekends for better sleep quality.
Good to know
- Cycle length varies individually (80–110 minutes) — treat 90 minutes as an average, not exact science.
- Sleep trackers that detect light sleep can complement this calculator for precision waking.