Sleep Calculator
Wake up refreshed by aligning with your natural 90-minute sleep cycles.
infoAssumes the average person takes 15 minutes to fall asleep, and each full sleep cycle lasts 90 minutes.
Recommended Bedtimes
9:45 PM
6 cycles · 9h sleep
in 8h 39m
Recommended11:15 PM
5 cycles · 7.5h sleep
in 10h 9m
12:45 AM
tomorrow
4 cycles · 6h sleep
in 11h 39m
2:15 AM
tomorrow
3 cycles · 4.5h sleep
in 13h 9m
Frequently Asked Questions
Why 90-minute sleep cycles?expand_more
Sleep occurs in cycles of roughly 90 minutes, moving through light sleep, deep sleep and REM sleep. Waking up mid-cycle, especially during deep sleep, tends to cause grogginess — waking between cycles feels more natural.
How many sleep cycles do I need?expand_more
Most adults need 5–6 full cycles (7.5–9 hours) per night for optimal rest, though this varies by individual and age.
Is this a substitute for medical sleep advice?expand_more
No. This tool gives a general estimate based on average sleep cycle length. If you experience ongoing sleep issues, consult a healthcare professional.