A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
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In China, teachers allow children to sleep in class for around 20 minutes to help improve their learning.
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If you hold farts in during the day, they'll just come out when you sleep.
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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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The higher someone’s I.Q. the more likely they are to be sleep deprived.
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47% of people have a nightmare at least once a month.
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