One reason that kittens sleep so much is because a growth hormone is released only during sleep.
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A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
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The average cat sleeps about 2/3 of the day.
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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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Studies show that the colder the room you sleep in, the more likely you are to have a bad dream.
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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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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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