Sleep Calculator
Enter your wake-up or bedtime to find optimal sleep times based on 90-minute sleep cycles.
How to Calculate
The Sleep Calculator finds optimal sleep/wake times based on 90-minute sleep cycles.
Sleep Cycles:
- 1 cycle = ~90 minutes
- ~15 minutes to fall asleep
- Recommended: 4-6 cycles (6-9 hours)
- Waking between cycles feels most refreshing
5 cycles (7h 30m) is ideal for most adults.
Example
FAQ
Why 90-minute cycles?
Human sleep repeats a cycle of light sleep, deep sleep, and REM sleep approximately every 90 minutes. Waking at the end of a cycle feels most refreshing.
Why add 15 minutes?
Most people take about 10-20 minutes to fall asleep, so 15 minutes is added as a default to account for the time it takes to actually start sleeping.