Sleep Cycle Calculator
Calculate your optimal sleep and wake times based on 90-minute sleep cycles. Wake up refreshed by timing your sleep to complete natural sleep cycles.
How to Use the Sleep Cycle Calculator
1. Choose Your Calculation Mode
Select "When to Sleep" if you know your wake-up time, or "When to Wake Up" if you know your bedtime.
2. Enter Your Time
Input your desired wake-up time or planned bedtime. Use the "Now" button for current time.
3. Review Your Options
Get multiple sleep time recommendations based on complete 90-minute sleep cycles.
Why Use Sleep Cycle Calculator?
- Based on scientific 90-minute sleep cycle research
- Helps you wake up during lighter sleep phases
- Reduces grogginess and improves morning alertness
- Accounts for 15 minutes to fall asleep
- Provides multiple options for different sleep durations
- Completely free with no registration required
Sleep Science Tip
Each sleep cycle lasts approximately 90 minutes and includes both light and deep sleep phases. Waking up at the end of a complete cycle helps you feel more refreshed than waking up in the middle of deep sleep.