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
Termites work 24 hours per day and they do not sleep.
57
A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
You forget 90% of your dreams.
256
Blue light fends off drowsiness in the middle of the night, which could be useful to people who work at night.
240
47% of people have a nightmare at least once a month.
186