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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If you hold farts in during the day, they'll just come out when you 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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Sleeping on your stomach can induce weirder, scarier, and sexier dreams.
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