A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
One reason that kittens sleep so much is because a growth hormone is released only during sleep.
212
Honeybees never sleep.
276
Those who get out of bed by 7am are more likely to be thinner and happier.
20
You forget 90% of your dreams.
256
In China, teachers allow children to sleep in class for around 20 minutes to help improve their learning.
13