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.
148
A new baby usually deprives each of it's parents around 350-400 hours of sleep in the first year. That is one entire nights sleep per week, per parent.
194
Cows can sleep standing up, but they can only dream lying down.
745
Sea otters hold hands while sleeping so they don’t drift away from each other.
104
The record for the longest scientifically documented period without sleep is 264.4 hours (eleven days).
15
In China, teachers allow children to sleep in class for around 20 minutes to help improve their learning.
13
Sleeping on your stomach can induce weirder, scarier, and sexier dreams.
22