Sleep Calculator
Wake up refreshed by timing your sleep cycles
You should try to fall asleep at:
10:15 PMExcellent
9 hours (6 cycles)
11:45 PMExcellent
7.5 hours (5 cycles)
01:15 AMGood
6 hours (4 cycles)
02:45 AMGood
4.5 hours (3 cycles)
04:15 AMShort
3 hours (2 cycles)
05:45 AMShort
1.5 hours (1 cycles)
How does it work?
The average human takes about 15 minutes to fall asleep and goes through 90-minute sleep cycles.
Waking up in the middle of a sleep cycle can leave you feeling tired and groggy (sleep inertia). Waking up at the end of a cycle helps you feel more refreshed and alert.
This calculator helps you time your sleep to complete 5 or 6 full cycles (7.5 to 9 hours of sleep).