Cows can sleep standing up, but they can only dream lying down.
745
The harder you concentrate on falling asleep, the less likely you are to fall asleep.
34
A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
In China, teachers allow children to sleep in class for around 20 minutes to help improve their learning.
13
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
If you hold farts in during the day, they'll just come out when you sleep.
16
A new parent will lose about 1055.6 hours of sleep in the first year of their child's life - almost 44 days!
6