In China, teachers allow children to sleep in class for around 20 minutes to help improve their learning.
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A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
Lack of water is the #1 trigger of daytime fatigue.
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The strangers in your dreams are actually people that you've seen in real life.
50
Staying awake for 17 hours is the same for your body as drinking 2 glasses of wine.
193
Cows can sleep standing up, but they can only dream lying down.
745
One reason that kittens sleep so much is because a growth hormone is released only during sleep.
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