Health & Daily Life
Sleep Cycle Calculator
Calculate optimal bedtimes and wake times based on 90-minute REM cycles.
Recommended Times (90-Minute Cycles)
A good night's rest consists of 5 to 6 complete 90-minute sleep cycles (including 15 mins to fall asleep).
How Sleep Cycle Calculator Works
Calculates optimal bedtimes and wake-up times aligned with natural 90-minute REM sleep cycles, helping users wake up during light sleep phases without grogginess.
Key Features
- Bidirectional calculation: plan bedtime from target alarm, or calculate alarm times from now.
- Accounts for the standard 15-minute physiological latency to fall asleep.
- Highlighted 5-cycle (7.5h) and 6-cycle (9h) optimal health recommendations.
Common Use Cases
- Sleep hygiene optimization, shift work scheduling, and eliminating morning fatigue.
Frequently Asked Questions
Why are sleep cycles 90 minutes long?
The human brain cycles through light sleep, deep slow-wave sleep, and REM dreaming approximately every 90 to 110 minutes.