Sleep Cycle Calculator
Enter your wake time or bedtime to find the optimal sleep times based on 90-minute sleep cycles.
Sleep in complete 90-minute cycles to wake feeling refreshed. Enter your desired wake time to find the best bedtimes (4, 5, or 6 complete cycles), or enter your bedtime to find the best wake times. Waking mid-cycle causes sleep inertia — that groggy feeling.
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Last reviewed: April 2026Report an error
Best Bedtimes
00:46
For a 07:00 wake-up, best bedtimes are 21:46 (6 cycles) or 23:16 (5 cycles).
Optimal (9h)
21:46
6 cycles
Good (7.5h)
23:16
5 cycles
Minimum (6h)
00:46
4 cycles
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How to Use This Sleep Cycles Calculator
- Choose: I know when I want to WAKE UP, or I know when I want to go to SLEEP.
- Enter your target time.
- Read the 3 ideal sleep or wake times corresponding to 4, 5, or 6 complete cycles.
- Choose the time that works for your schedule.
Frequently Asked Questions
- A full sleep cycle (light sleep → deep sleep → REM) averages 90 minutes. Adults need 4–6 cycles per night (6–9 hours). Waking mid-cycle disrupts the process.
- The average person takes about 14 minutes to fall asleep. This calculator accounts for a 14-minute fall-asleep window by default.
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