Scientists Hint at Why Laughter Feels So Good

http://www.nytimes.com/2011/09/14/science/14laughter.html?partner=rss&emc=rss

The results, when analyzed, showed that laughing increased pain resistance, whereas simple good feeling in a group setting did not.

Pain resistance is used as an indicator of endorphin levels because their presence in the brain is difficult to test; the molecules would not appear in blood samples because they are among the brain chemicals that are prevented from entering circulating blood by the so-called blood brain barrier.