A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
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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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A new parent will lose about 1055.6 hours of sleep in the first year of their child's life - almost 44 days!
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The record for the longest scientifically documented period without sleep is 264.4 hours (eleven days).
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Sea otters hold hands while sleeping so they don’t drift away from each other.
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There's a love mattress that is specifically designed for couples who sleep on each other's arms.
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Bats sleep 18-20 hours per day.
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