The human brain is more active during sleep than during the day.
28
Cows can sleep standing up, but they can only dream lying down.
745
A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
Bats sleep 18-20 hours per day.
5
Dieters who sleep more take off more fat that those who sleep less.
159
Sleeping on your stomach can induce weirder, scarier, and sexier dreams.
22
47% of people have a nightmare at least once a month.
186