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
47% of people have a nightmare at least once a month.
186
One reason that kittens sleep so much is because a growth hormone is released only during sleep.
212
Sea otters hold hands while sleeping so they don’t drift away from each other.
104
44% of kids watch television before they go to sleep.
106
In China, teachers allow children to sleep in class for around 20 minutes to help improve their learning.
13
The human brain is more active during sleep than during the day.
28