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
Bats sleep 18-20 hours per day.
5
In China, teachers allow children to sleep in class for around 20 minutes to help improve their learning.
13
The strangers in your dreams are actually people that you've seen in real life.
50
Termites work 24 hours per day and they do not sleep.
57
Cows can sleep standing up, but they can only dream lying down.
745
If you hold farts in during the day, they'll just come out when you sleep.
16