Sleeping on your stomach can induce weirder, scarier, and sexier dreams.
22
The average cat sleeps about 2/3 of the day.
203
Cows can sleep standing up, but they can only dream lying down.
745
Bats sleep 18-20 hours per day.
5
The human brain is more active during sleep than during the day.
28
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