90-Minute Sleep Cycle Science

Sleep Calculator

Wake up between sleep cycles feeling refreshed and energized instead of groggy.

Select your desired wake-up time:

Time to fall asleep:

min

1 Sleep cycle length:

min

Recommended Bedtimes

Why Sleep Cycles Matter: A good night's sleep consists of 5 to 6 complete sleep cycles. Waking up in the middle of a deep sleep stage leaves you feeling groggy and exhausted (sleep inertia), whereas waking up during light transitions between cycles helps you feel alert immediately.