There's a love mattress that is specifically designed for couples who sleep on each other's arms.
12
A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
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One reason that kittens sleep so much is because a growth hormone is released only during sleep.
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Cows can sleep standing up, but they can only dream lying down.
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Termites work 24 hours per day and they do not sleep.
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Sea otters hold hands while sleeping so they don’t drift away from each other.
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