Cows can sleep standing up, but they can only dream lying down.
745
People who sleep late have more mental stamina and can outperform early risers.
33
One reason that kittens sleep so much is because a growth hormone is released only during sleep.
212
47% of people have a nightmare at least once a month.
186
The average cat sleeps about 2/3 of the day.
203
A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
Bats sleep 18-20 hours per day.
5