Sleep Cycle Calculator
Find the best bedtime or wake-up time based on 90-minute sleep cycles.
Go to bed at one of these times
9:45 PM
6 cycles
10:30 PM
5.5 cycles
11:15 PM
5 cycles
12:00 AM
4.5 cycles
12:45 AM
4 cycles
1:30 AM
3.5 cycles
Frequently asked questions
- Why 90-minute cycles?
- A full sleep cycle (light sleep, deep sleep, and REM) lasts roughly 90 minutes. Waking up at the end of a cycle, rather than in the middle of one, tends to feel less groggy.
- Why add 15 minutes?
- That's a typical estimate for the time it takes to actually fall asleep after getting into bed.
- How many cycles should I aim for?
- Five to six cycles (7.5–9 hours) covers most adults, but everyone is a little different.