47% of people have a nightmare at least once a month.
186
The harder you concentrate on falling asleep, the less likely you are to fall asleep.
34
Cows can sleep standing up, but they can only dream lying down.
745
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
In China, teachers allow children to sleep in class for around 20 minutes to help improve their learning.
13
Studies show that the colder the room you sleep in, the more likely you are to have a bad dream.
28