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
Studies show that the colder the room you sleep in, the more likely you are to have a bad dream.
28
If you hold farts in during the day, they'll just come out when you sleep.
16
The human brain is more active during sleep than during the day.
28
People who sleep late have more mental stamina and can outperform early risers.
33
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