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Sleep Cycles Explained

5-minute read 20 XP in app 7 cards

Sleep is not one thing

A full night consists of 4-5 cycles, each ~90 minutes. Each contains light sleep, deep sleep, and REM — all serving different functions.

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Slide to guess the optimal sleep duration recommended by science.

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Fact

During deep sleep, growth hormone is released, tissues repair, and your glymphatic system flushes toxins from the brain.

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Tap each stage to discover what your body is actually doing.

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You spend more time in REM sleep in the first half of the night.

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See what happens as sleep debt accumulates night by night.

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Takeaway

Prioritising 7-9 hours gives your brain time to complete all repair cycles. Deep sleep repairs your body; REM restores your mind.