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
Studies show that the colder the room you sleep in, the more likely you are to have a bad dream.
28
Cows can sleep standing up, but they can only dream lying down.
745
One reason that kittens sleep so much is because a growth hormone is released only during sleep.
212
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
Bats sleep 18-20 hours per day.
5