Sleep Calculator
Wake up refreshed by timing your sleep to complete REM cycles
How it works:
Sleep occurs in 90-minute REM cycles. Waking at the end of a cycle means you feel refreshed instead of groggy. We add 14 minutes to fall asleep.
Go to sleep at…
1
5:16 AM
1 cycles · 1h 30m sleep
☠️ Terrible
2
3:46 AM
2 cycles · 3h sleep
😴 Poor
3
2:16 AM
3 cycles · 4h 30m sleep
😐 Okay
4
12:46 AM
4 cycles · 6h sleep
😊 Good
5
11:-44 PM
5 cycles · 7h 30m sleep
🌟 GreatRecommended
6
9:-14 PM
6 cycles · 9h sleep
💪 OptimalRecommended
Pro tip: Adults need 5–6 complete sleep cycles (7.5–9 hours). Less than 4 cycles impairs focus, memory, and immune function.