A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
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Sleeping on your stomach can induce weirder, scarier, and sexier dreams.
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The record for the longest scientifically documented period without sleep is 264.4 hours (eleven days).
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47% of people have a nightmare at least once a month.
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44% of kids watch television before they go to sleep.
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The average person falls asleep in seven minutes.
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The human brain is more active during sleep than during the day.
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