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 human brain is more active during sleep than during the day.
28
Bats sleep 18-20 hours per day.
5
The higher someone’s I.Q. the more likely they are to be sleep deprived.
29
Studies show that the colder the room you sleep in, the more likely you are to have a bad dream.
28
The average cat sleeps about 2/3 of the day.
203
One reason that kittens sleep so much is because a growth hormone is released only during sleep.
212
People who sleep late have more mental stamina and can outperform early risers.
33