In an article recently published in the British Medical Journal, researchers examined the extensive Framingham, Massachusetts data from 1983 to 2003 that looked at a social network of over 4,000 people and their neighbors, acquaintances, friends, and spouses (who actually had less effect on happiness than friends!). Approximately 50,000 social ties were represented on the questionnaires the subjects filled out. The BMJstudy concluded that there was a group happiness factor, that "peoples' happiness depends on the happiness of others with whom they are connected. This provides further justification for seeing happiness, like health, as a collective phenomenon."

Critics of the study quickly pointed out in another study published in the same journal that other environmental factors the subjects had in common may have caused the effects of apparent contagious happiness.

Here is my take:

* The Framingham data was compiled mainly to study heart disease, but reanalyzing it now to look for social networking clues is interesting. This analysis may lack a certain observer bias. The original researchers who compiled the information could not be influenced since they did not have "happiness" in mind. * On the other hand, data obtained about happiness by questionnaire are often weak, and further studies would have to be done before any firm observations could be made. It is quite possible that the perceived socially connected happiness may be another factor that the subjects had in common. * But it is certainly interesting to consider that happiness, like worry, may be infectious. In my book "False Alarm; the Truth About the Epidemic of Fear," I looked at the effects of transmitted worry on the negative health of our society. It is reasonable to consider the opposite - that if those around you are happy and have a positive attitude, you may be less likely to become stressed and ultimately ill. This phenomena could involve emotional as well as hormonal triggers.

The expression "be happy, be healthy," could end up being more than just a gratuitous expression.

Dr. Marc Siegel is an internist and associate professor of medicine at the NYU School of Medicine. He is a FOX News Medical Contributor and writes a health column for LA Times, where he examines TV and movies for medical accuracy. Dr. Siegel is the author of "False Alarm: the Truth About the Epidemic of Fear" and "Bird Flu: Everything You Need to Know About the Next Pandemic." Read more at www.doctorsiegel.com

Dr. Marc Siegel, a practicing internist, joined FOX News Channel (FNC) as a contributor in 2008..