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Wake up refreshed by timing your sleep in 90-minute cycles.
How long is one sleep cycle?
A full sleep cycle lasts about 90 minutes and moves through light sleep, deep sleep, and REM. Waking up at the end of a cycle instead of in the middle of one helps you feel far more rested.
How many sleep cycles do I need per night?
Most adults need 5 to 6 cycles, which is about 7.5 to 9 hours of sleep. Aim for at least 5 cycles; regularly getting 4 or fewer can leave you tired and unfocused during the day.