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
A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
You burn more calories sleeping than you do watching television.
348
One reason that kittens sleep so much is because a growth hormone is released only during sleep.
212
Dieters who sleep more take off more fat that those who sleep less.
159
In China, teachers allow children to sleep in class for around 20 minutes to help improve their learning.
13
Studies show that the colder the room you sleep in, the more likely you are to have a bad dream.
28
A new baby usually deprives each of it's parents around 350-400 hours of sleep in the first year. That is one entire nights sleep per week, per parent.
194