Blue light fends off drowsiness in the middle of the night, which could be useful to people who work at night.
240
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
A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
Termites work 24 hours per day and they do not sleep.
57