A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
In China, teachers allow children to sleep in class for around 20 minutes to help improve their learning.
13
Lack of water is the #1 trigger of daytime fatigue.
148
If you hold farts in during the day, they'll just come out when you sleep.
16
Sea otters hold hands while sleeping so they don’t drift away from each other.
104
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
Blue light fends off drowsiness in the middle of the night, which could be useful to people who work at night.
240
The strangers in your dreams are actually people that you've seen in real life.
50