Sea otters hold hands while sleeping so they don’t drift away from each other.
104
The strangers in your dreams are actually people that you've seen in real life.
50
A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
The record for the longest scientifically documented period without sleep is 264.4 hours (eleven days).
15
Studies show that the colder the room you sleep in, the more likely you are to have a bad dream.
28
Cows can sleep standing up, but they can only dream lying down.
745