Sea otters hold hands while sleeping so they don’t drift away from each other.
104
You burn more calories sleeping than you do watching television.
348
A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
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
Lack of water is the #1 trigger of daytime fatigue.
148