Sleep Duration Calculator
Find optimal bedtimes based on 90-minute sleep cycles and your wake-up time.
Calculator
Time you typically need to fall asleep after going to bed
How to Use
- Set your planned wake-up time
- Enter how long it takes you to fall asleep (default 15 min)
- Choose your preferred number of sleep cycles
- View your recommended bedtime and alternative options
FAQ
Q: What are sleep cycles?
A: A sleep cycle lasts about 90 minutes and includes all stages of sleep from light to deep and REM. Waking between cycles helps you feel more refreshed.
Q: How many cycles do I need?
A: Most adults need 5-6 cycles (7.5–9 hours) per night. Start with 5 and adjust based on how you feel.
Q: Why does waking mid-cycle feel bad?
A: Waking during deep sleep (middle of a cycle) disrupts your brain's processing. You feel groggy because you're pulled out of deep sleep abruptly.