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
Quick naps not only improve your alertness, but they also help in decision making, creativity and sensory perception.
149
Cows can sleep standing up, but they can only dream lying down.
745
Bats sleep 18-20 hours per day.
5
Dieters who sleep more take off more fat that those who sleep less.
159
People who sleep late have more mental stamina and can outperform early risers.
33
A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
One reason that kittens sleep so much is because a growth hormone is released only during sleep.
212