Re: what is the biologic effects of smiling and laughing?

Hi Zehra-

      That's a great question. I was thinking about it - is it that when we feel good, we smile, or is it that when we smile, we feel good?

      It doesn't seem that we have a definite answer to that question. Probing through the literature, however, it seems that there is a growing body of evidence that our brains "listen" to our bodies to develop our mood and emotion. With relation to smiling, one study, summarized, says

"This study examined the effects of forced laughter on mood and compared laughter with two other possible mood-improving activities, smiling and howling. While howling did not substantially improve mood, both smiling and laughing did. Moreover, laughter seemed to boost positive affect more than just smiling by 22 adults." - Neuhoff & Schaefer, Psychol Rep Dec 91, 1079-80 (2002)

      As you may know, smiling has an interesting curiousity: we can tell the difference between a 'fake' or forced smile, and one that is elicited from true enjoyment or happiness (called a "Duchenne smile"). Duchenne was a French neurologist and researcher in the early 1800's. His pioneering work in muscle control showed that the different types of smiles are because different sets of muscles are utilized. Perhaps your brain reads a Duchenne smile to mean your happy! It would be interesting to test that...

      More research, including several books by Antonio Damasio (most notable, Descartes' Error) suggest that in general, our brain pays attention to cues from the rest of our body to determine our moods and emotions. I highly recommend the book - it's a fascinating read!

      I hope that helps answer your question, or at least leads you to some interesting reading!

-Alex G
cgoddard@fas.harvard.edu