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
Bats sleep 18-20 hours per day.
5
The higher someone’s I.Q. the more likely they are to be sleep deprived.
29
A new parent will lose about 1055.6 hours of sleep in the first year of their child's life - almost 44 days!
6
The harder you concentrate on falling asleep, the less likely you are to fall asleep.
34