Sleep Cycle Calculator: Find Your Ideal Bedtime
A free bedtime calculator and wake up calculator. Your sleep comes in 90-minute cycles, and waking up between cycles leaves you refreshed instead of groggy. Pick a mode and see your ideal times.
Go to bed at one of these times
Times include a 15-minute buffer to fall asleep. 5 to 6 full cycles are recommended.
How the sleep cycle calculator works
- Each sleep cycle lasts about 90 minutes, from light sleep through deep sleep to REM.
- Most people need around 15 minutes to fall asleep, so the calculator adds that buffer.
- Pick your bedtime or wake-up time and choose a full number of cycles so your alarm lands between cycles.
Sleep cycle questions
What is a sleep cycle?
A sleep cycle is the full pass through the stages of sleep, from light sleep to deep sleep to REM sleep. One complete cycle lasts about 90 minutes, and most adults go through several cycles each night.
How many sleep cycles do I need per night?
Most adults feel their best with 5 to 6 full sleep cycles per night, which is 7.5 to 9 hours of sleep. Waking at the end of a cycle, instead of in the middle of deep sleep, is the key to waking up refreshed.
What is the 90-minute rule for sleep?
The 90-minute rule says sleep moves in roughly 90-minute blocks. Timing your bedtime or your alarm to a multiple of 90 minutes helps you wake between cycles, when sleep is lightest, instead of from deep sleep, when grogginess is worst.