A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
Blue light fends off drowsiness in the middle of the night, which could be useful to people who work at night.
240
The human brain is more active during sleep than during the day.
28
The average cat sleeps about 2/3 of the day.
203
Dieters who sleep more take off more fat that those who sleep less.
159