Slumber

Sleep cycle calculator · Wake up refreshed

Go to bed at one of these times:

Includes ~15 minutes to fall asleep

How it works

Sleep happens in 90-minute cycles. Each cycle moves through light sleep, deep sleep, and REM.

Waking up between cycles (rather than mid-cycle) helps you feel alert instead of groggy. Slumber calculates optimal times based on complete cycles.

Adults need 5-6 cycles (7.5-9 hours) per night. 4 cycles (6 hours) is the minimum for most people.

Recommended sleep by age

Teens (14-17)8-10h
Young adults (18-25)7-9h
Adults (26-64)7-9h
Older adults (65+)7-8h