Sleep Cycle Calculator
Find the perfect time to wake up or go to bed to align with your body's natural 90-minute sleep cycles (REM).
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Understanding Sleep Cycles
A sleep cycle lasts about 90 minutes, during which you move through five stages of sleep. The first four stages make up our non-rapid eye movement (NREM) sleep, and the fifth stage is when rapid eye movement (REM) sleep occurs.
Waking up in the middle of a sleep cycle leaves you feeling groggy and tired (sleep inertia). Waking up between cycles usually makes you feel refreshed and alert.