Cows can sleep standing up, but they can only dream lying down.
745
One reason that kittens sleep so much is because a growth hormone is released only during sleep.
212
The record for the longest scientifically documented period without sleep is 264.4 hours (eleven days).
15
Blue light fends off drowsiness in the middle of the night, which could be useful to people who work at night.
240
In China, teachers allow children to sleep in class for around 20 minutes to help improve their learning.
13
The harder you concentrate on falling asleep, the less likely you are to fall asleep.
34
47% of people have a nightmare at least once a month.
186