Sleep Calculator
Find the best wake-up times based on 90-minute sleep cycles if you go to bed at a given time.
How This Works
A full sleep cycle lasts about 90 minutes, moving through light sleep, deep sleep and REM sleep. Waking up at the end of a cycle (rather than in the middle of one) generally feels more refreshing. We also add about 15 minutes for the average time it takes to fall asleep.
Formula
Example
Falling asleep at 11:00 PM with 5 full cycles (7.5 hours of sleep) puts your wake-up time at approximately 6:45 AM.
Frequently Asked Questions
What time should I wake up if I go to bed at 11:00 PM?
Good options are 3:45 AM (4.5h), 5:15 AM (6h), 6:45 AM (7.5h), 8:15 AM (9h).
Why 90-minute increments?
A full sleep cycle lasts approximately 90 minutes. Waking up at the end of a cycle, rather than mid-cycle, tends to feel less groggy.