Sleep Cycle Calculator

Find the best time to wake up or go to sleep. Sleep happens in 90-minute cycles, and waking between cycles helps you feel refreshed instead of groggy.

Calculate from

Wake time (find bedtime) Sleep time (find wake time)

When do you need to wake up?

How sleep cycles work

Sleep happens in roughly 90-minute cycles (between 80-120 minutes). Each cycle has stages:

Light sleep — easy to wake from
Deep sleep — body repairs itself
REM sleep — dreaming and memory consolidation

If you wake during deep sleep, you feel groggy (sleep inertia). If you wake between cycles or during light sleep, you feel refreshed.

Pro tip: It takes most people 10-15 minutes to fall asleep. This calculator adds 15 minutes to account for that.

Want a deeper guide?

Read: Sleep Cycles Explained: Why You Wake Up Groggy (and How to Fix It) — why sleep timing helps, what sleep inertia is, and when a calculator is only part of the answer.

Read the sleep guide →