Sleep Cycle Calculator
Find the best times to sleep or wake up based on 90-minute sleep cycles. Wake up feeling refreshed by completing full cycles.
Sleep Cycle Calculator
Find the best times to sleep or wake up based on 90-minute sleep cycles
How to Use This Calculator
- 1
Choose your mode
Select whether you need to wake up at a specific time or want to go to bed at a specific time.
- 2
Enter your time
Input your target wake-up time or bedtime.
- 3
Adjust fall asleep time
Enter how long it typically takes you to fall asleep (default 15 minutes).
- 4
View recommended times
See optimal sleep/wake times based on complete 90-minute cycles.
Frequently Asked Questions
What is a sleep cycle?
A sleep cycle lasts about 90 minutes and includes light sleep, deep sleep, and REM sleep. Waking at the end of a cycle (rather than mid-cycle) helps you feel more refreshed.
How many sleep cycles do I need?
Most adults need 4-6 complete cycles (6-9 hours) per night. 5-6 cycles is optimal for most people. Quality matters as much as quantity.
Why do I feel tired after 8 hours of sleep?
You may be waking mid-cycle. Try adjusting your sleep time by 15-30 minutes to align with cycle completion. Sleep quality, consistency, and sleep disorders also affect how rested you feel.