A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
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The human brain is more active during sleep than during the day.
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The record for the longest scientifically documented period without sleep is 264.4 hours (eleven days).
15
Termites work 24 hours per day and they do not sleep.
57
If you hold farts in during the day, they'll just come out when you sleep.
16
You forget 90% of your dreams.
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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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