Sleep Cycle Calculator
Wake up refreshed by timing your alarm to natural 90-minute sleep cycles. Pick whether you want bedtimes for a set wake-up time, or wake-up times for a set bedtime — the best options appear instantly, ranked by cycle count.
Recommended bedtimes
How to use
- Choose whether you want the best bedtime or the best wake-up time.
- Set your fixed time and how long it usually takes you to fall asleep (default 15 minutes).
- Pick one of the suggested options — more cycles means deeper, more refreshing rest.
Note: Each cycle is 90 minutes. Results step back or forward in whole cycles from your time, minus fall-asleep time. General information only, not medical advice — talk to a doctor if you have a sleep problem.
Tips
- Most adults feel best with 5 to 6 cycles (about 7.5 to 9 hours in bed).
- Keep the same wake-up time every day, even on weekends — it trains your body clock.
- Dim screens 30 minutes before bed so the fall-asleep time stays short.
Frequently Asked Questions (FAQ)
How long is one sleep cycle?
One full sleep cycle lasts about 90 minutes. Waking up at the end of a cycle feels easier than waking in the middle of one.
How many sleep cycles do I need?
Most adults do well with 5 to 6 cycles, which is about 7.5 to 9 hours in bed including the time to fall asleep.
Why does waking up mid-cycle feel so bad?
Waking during deep sleep interrupts the cycle, which causes grogginess. Timing your alarm to a cycle boundary avoids that.
How do I find the best bedtime or wake-up time?
Choose whether you know your wake-up time or your bedtime, then enter that time and your fall-asleep minutes. The tool lists the best options instantly, ranked by cycle count.