Sleep Cycle Calculator
Find the best times to fall asleep or wake up based on 90-minute sleep cycles.
Use Sleep Cycle Calculator ↓Sleep Cycle Calculator
Find the best times to fall asleep or wake up based on 90-minute sleep cycles. Waking between cycles helps you feel refreshed instead of groggy.
Recommended Bedtimes
Frequently Asked Questions
How many sleep cycles do I need per night?
Most adults need 5-6 complete sleep cycles (7.5-9 hours) per night. Each cycle lasts approximately 90 minutes and includes light sleep, deep sleep, and REM sleep stages.
Why do I feel groggy when my alarm goes off?
Grogginess, called sleep inertia, occurs when you wake during deep sleep or mid-cycle. Timing your alarm to the end of a complete 90-minute cycle helps you wake during lighter sleep, reducing that groggy feeling.
Does it really take 14 minutes to fall asleep?
The average adult takes 10-20 minutes to fall asleep, with 14 minutes being a commonly cited average. This calculator accounts for this sleep onset latency when computing bedtimes.