In China, teachers allow children to sleep in class for around 20 minutes to help improve their learning.
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A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
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The harder you concentrate on falling asleep, the less likely you are to fall asleep.
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Cows can sleep standing up, but they can only dream lying down.
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The higher someone’s I.Q. the more likely they are to be sleep deprived.
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Dieters who sleep more take off more fat that those who sleep less.
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47% of people have a nightmare at least once a month.
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