Wake up refreshed with the perfect sleep timing
Based on 90-minute sleep cycles β the science of waking up at the right moment.
π‘ Green = recommended (7.5β9 hours). Waking at the end of a cycle feels easiest.
How the sleep cycle calculator works
Human sleep runs in cycles of roughly 90 minutes, moving from light sleep to deep sleep and REM. Waking up in the middle of deep sleep causes grogginess β waking at the end of a cycle feels natural and refreshing.
- 1 cycle β 90 minutes
- Most adults need 5β6 cycles (7.5β9 hours)
- Falling asleep takes ~15 minutes on average β added automatically
If you must wake at 7:00 AM, going to bed at 11:15 PM (5 full cycles) feels far better than midnight, even though it is less total sleep. Timing beats duration.
FAQ
How long is a sleep cycle?
An average sleep cycle lasts about 90 minutes. Most adults need 4 to 6 full cycles (6 to 9 hours) per night.
Is it better to wake up at the end of a sleep cycle?
Yes. Waking during light sleep at the end of a 90-minute cycle usually feels much easier than being jolted out of deep sleep.
How long does it take to fall asleep?
On average about 15 minutes. This calculator adds a 15-minute buffer when computing bedtimes.
What is the best time to go to sleep?
There is no single best time β it depends on when you must wake up. Count backwards in 90-minute cycles from your alarm, minus 15 minutes to fall asleep.