A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
The record for the longest scientifically documented period without sleep is 264.4 hours (eleven days).
15
The harder you concentrate on falling asleep, the less likely you are to fall asleep.
34
Bats sleep 18-20 hours per day.
5
Cows can sleep standing up, but they can only dream lying down.
745
Quick naps not only improve your alertness, but they also help in decision making, creativity and sensory perception.
149
47% of people have a nightmare at least once a month.
186