A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
People who sleep late have more mental stamina and can outperform early risers.
33
The higher someone’s I.Q. the more likely they are to be sleep deprived.
29
Lack of water is the #1 trigger of daytime fatigue.
148
Blue light fends off drowsiness in the middle of the night, which could be useful to people who work at night.
240
The average cat sleeps about 2/3 of the day.
203
The average person falls asleep in seven minutes.
115
Some people have a "natural alarm clock" allowing them to wake up when they want. This is actually caused by a burst of the stress hormone adrenocorticotropin.
15