<http://schema.org/description>
"Researchers have had such a hard time trying to determine why we sleep that there&amp;#039;s an old joke in the sleep scientist community: &amp;quot;We need sleep to cure sleepiness.&amp;quot; Have they come up with any other theories?"^^<http://www.w3.org/2001/XMLSchema#string>
<http://health.howstuffworks.com/mental-health/sleep/basics/why-do-we-sleep1.htm>