Dieters who sleep more take off more fat that those who sleep less.
159
Blue light fends off drowsiness in the middle of the night, which could be useful to people who work at night.
240
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
The harder you concentrate on falling asleep, the less likely you are to fall asleep.
34