In China, teachers allow children to sleep in class for around 20 minutes to help improve their learning.
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Studies show that the colder the room you sleep in, the more likely you are to have a bad dream.
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A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
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Honeybees never sleep.
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You forget 90% of your dreams.
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Cows can sleep standing up, but they can only dream lying down.
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Sea otters hold hands while sleeping so they don’t drift away from each other.
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