A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
People who sleep late have more mental stamina and can outperform early risers.
33
Some people have a "natural alarm clock" allowing them to wake up when they want. This is actually caused by a burst of the stress hormone adrenocorticotropin.
15
47% of people have a nightmare at least once a month.
186
44% of kids watch television before they go to sleep.
106
One reason that kittens sleep so much is because a growth hormone is released only during sleep.
212