Sleep Calculator
Optimize your sleep by waking up between sleep cycles.
I want to wake up at...
I'm going to bed at...
How it works: A full sleep cycle lasts about 90 minutes, and a good night's sleep consists of 5-6 complete cycles (7.5-9 hours). Waking up between cycles — rather than in the middle of one — helps you feel more refreshed. This calculator also accounts for the average time it takes to fall asleep.