A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
Honeybees never sleep.
276
Sleeping on your stomach can induce weirder, scarier, and sexier dreams.
22
Cows can sleep standing up, but they can only dream lying down.
745
47% of people have a nightmare at least once a month.
186
The harder you concentrate on falling asleep, the less likely you are to fall asleep.
34