A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
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In China, teachers allow children to sleep in class for around 20 minutes to help improve their learning.
13
The higher someone’s I.Q. the more likely they are to be sleep deprived.
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There's a love mattress that is specifically designed for couples who sleep on each other's arms.
12
The average person falls asleep in seven minutes.
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