A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
Those who get out of bed by 7am are more likely to be thinner and happier.
20
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
The higher someone’s I.Q. the more likely they are to be sleep deprived.
29
You burn more calories sleeping than you do watching television.
348
The human brain is more active during sleep than during the day.
28