Studies show that the colder the room you sleep in, the more likely you are to have a bad dream.
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Bats sleep 18-20 hours per day.
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A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
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47% of people have a nightmare at least once a month.
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The average cat sleeps about 2/3 of the day.
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Sea otters hold hands while sleeping so they don’t drift away from each other.
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