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Sleep REM Cycle Calculator

Find the best time to wake up or go to sleep based on 90-minute REM sleep cycles. Wake up feeling refreshed by aligning your alarm with the end of a complete sleep cycle.

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Optimize your wake times and bedtimes using the standard 90-minute REM sleep cycle model. Perfect for shift workers, new parents, students, and anyone looking to reduce morning grogginess.

The Science Behind Sleep Cycles

A full sleep cycle lasts approximately 90 minutes and includes both NREM (non-rapid eye movement) and REM (rapid eye movement) stages. Waking up at the end of a cycle — when sleep is lightest — helps you feel more refreshed and alert. This calculator uses the standard 90-minute cycle model endorsed by the National Sleep Foundation and the American Academy of Sleep Medicine.

Fun Fact: The average person experiences 4-6 complete sleep cycles per night. The first REM cycle is the shortest (about 10 minutes), while the last one before waking can last up to 60 minutes!

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