Calculate optimal bedtime or wake time based on 90-minute sleep cycles. Wake up refreshed by timing your sleep cycles perfectly.
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A complete sleep cycle lasts approximately 90 minutes and includes all stages of sleep: light sleep, deep sleep, and REM (Rapid Eye Movement) sleep. Waking up at the end of a complete cycle, rather than in the middle of deep sleep, helps you feel more refreshed and alert.
The 90-minute cycle is based on the natural rhythm of REM sleep. Each cycle progresses through different sleep stages, with REM sleep typically occurring at the end of each cycle. Waking during REM sleep or light sleep is much easier than waking from deep sleep.
On average, it takes about 14 minutes for most people to fall asleep. This calculator accounts for this time, so you can plan your bedtime more accurately and wake up feeling refreshed.
Most adults need 7-9 hours of sleep per night. The calculator provides options for 4 cycles (6 hours), 5 cycles (7.5 hours - recommended), and 6 cycles (9 hours). The 5-cycle option is typically the best balance for most people.