Sleep Calculator
Find the perfect bedtime or wake-up time based on 90-minute sleep cycles.
About Sleep Cycles
Sleep happens in ~90-minute cycles through light, deep, and REM stages. Waking at the end of a complete cycle — not mid-cycle — leaves you feeling alert and refreshed. Most adults need 5–6 cycles (7.5–9 hours) nightly.
Sleep Cycle Tips
| Cycles | Total Sleep | Recommendation |
|---|---|---|
| 3 cycles | 4.5 hours | Too little |
| 4 cycles | 6.0 hours | Minimum |
| 5 cycles | 7.5 hours | Optimal |
| 6 cycles | 9.0 hours | Optimal |
| 7 cycles | 10.5 hours | Extra rest |
This calculator is for educational purposes only. Consult a qualified healthcare professional for medical advice.