Sleep Calculator
Find the best times to sleep or wake up based on 90-minute sleep cycles. Waking between cycles helps you feel more refreshed.
Go to bed at Wake up at
Recommended
cycles
hours
How Sleep Cycles Work
| Cycles | Sleep Time | Total (incl. 14 min to fall asleep) |
|---|---|---|
| 6 | 9h 0m | 9h 14m |
| 5 | 7h 30m | 7h 44m |
| 4 | 6h 0m | 6h 14m |
| 3 | 4h 30m | 4h 44m |
Sleep Tips
- Each sleep cycle lasts about 90 minutes.
- It takes an average of 14 minutes to fall asleep.
- Most adults need 5-6 complete cycles (7.5-9 hours) per night.
- Waking up between cycles helps you feel more refreshed.
Frequently Asked Questions
How many hours of sleep do I need?
Adults typically need 7–9 hours of sleep per night, according to the National Sleep Foundation. Teenagers need 8–10 hours, school-age children need 9–11 hours, and newborns need 14–17 hours. Individual needs vary; consistently waking without an alarm is a good sign of sufficient sleep.
What is a sleep cycle and why does it matter?
A sleep cycle lasts approximately 90 minutes and includes light sleep, deep sleep, and REM (dreaming) sleep. Waking at the end of a complete cycle (rather than mid-cycle) helps you feel more refreshed. This is why sleeping 7.5 hours (5 cycles) can feel better than 8 hours (mid-cycle).
What is sleep latency and how does it affect bedtime?
Sleep latency is the time it takes to fall asleep after getting into bed, typically 10–20 minutes for healthy adults. When calculating your ideal bedtime, add 15 minutes of sleep latency to the number of sleep cycles you need. Falling asleep in under 5 minutes may indicate sleep deprivation.