Sleep Cycle Calculator
Calculate the best time to wake up or go to sleep based on 90-minute sleep cycles.
Age Range
Sleep Schedule
How It Works
This calculator is based on the science of sleep cycles. Sleep occurs in cycles of approximately 90 minutes, moving between light sleep, deep sleep, and REM (Rapid Eye Movement) sleep. Waking up in the middle of a sleep cycle can leave you feeling groggy and tired, even if you've had a lot of sleep. This tool calculates optimal bedtimes or wake-up times by working backward or forward in 90-minute increments from your desired time. It also accounts for the average 15 minutes it takes most people to fall asleep, helping you wake up at the end of a natural sleep cycle so you feel refreshed and energized.
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