The average cat sleeps about 2/3 of the day.
203
Bats sleep 18-20 hours per day.
5
A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
You burn more calories sleeping than you do watching television.
348
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
The strangers in your dreams are actually people that you've seen in real life.
50
In China, teachers allow children to sleep in class for around 20 minutes to help improve their learning.
13