A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
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The average person falls asleep in seven minutes.
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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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47% of people have a nightmare at least once a month.
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A new baby usually deprives each of it's parents around 350-400 hours of sleep in the first year. That is one entire nights sleep per week, per parent.
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Sea otters hold hands while sleeping so they don’t drift away from each other.
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The record for the longest scientifically documented period without sleep is 264.4 hours (eleven days).
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