Sleep Calculator
Optimal bedtime or wake time based on 90-minute sleep cycles and fall-asleep latency.
How to Use
- Pick whether you know wake time or bed time.
- Recommended alternates are spaced by full cycles.
Input
Recommended times
Basis
Sleep cycle
~90 minutes — waking mid-cycle feels groggy
Adult target
5-6 cycles · 7.5-9 hours in bed
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