Cows can sleep standing up, but they can only dream lying down.
745
Blue light fends off drowsiness in the middle of the night, which could be useful to people who work at night.
240
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
A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
People who sleep late have more mental stamina and can outperform early risers.
33
The average cat sleeps about 2/3 of the day.
203
The human brain is more active during sleep than during the day.
28