Calculate bedtimes and wake-up times based on 90-minute sleep cycles.
The Sleep Cycle Calculator calculates the times when it is best to fall asleep or wake up, so you wake up during the light sleep phase. Sleep progresses in approximately 90-minute cycles, and waking up should coincide with the end of a cycle.
The calculator is free, works in your browser without registration, and shows the result as soon as you change the values. The calculation is done on your device, and the information you enter is not sent anywhere.
One sleep cycle lasts about 90 minutes. The calculator adds 15 minutes to falling asleep and calculates times based on 4–6 cycles.
If you want to wake up at 7:00 AM, you should aim to fall asleep around 9:45 PM (6 cycles), 11:15 PM (5 cycles), or 12:45 AM (4 cycles), allowing 15 minutes to fall asleep. With default settings, the calculator gives the result: Best bedtime 21:45.
For anyone who wants to wake up feeling more refreshed and plan their sleep duration.
An adult typically needs 5–6 cycles, or 7.5–9 hours of sleep. The need is individual.
No. The length of a cycle varies between individuals, ranging from 80 to 110 minutes. The calculator provides a guideline.
Waking up from deep sleep feels heavy. Waking up during the light sleep phase makes mornings easier.