Happiness is Contagious, If Not For a Fleeting Moment

According to a twenty-year longitudinal study of over 4000 individuals, happiness is indeed contagious. Dr. Nicholas Christakis, professor at Harvard University, compared the spread of happiness to a “ripple effect” that could affect others up to three degrees of separation away; a friend of a friend of a friend, so to speak.

The study did not actually determine the mechanisms of how happiness could be spread, but there were several hypotheses presented from happy people sharing their good fortune to simply exhibiting genuinely contagious emotions. Friends, spouses, live-in partners, roommates, siblings, and neighbors; all of these people would have an effect on their social circles’ happiness.

There is one exception in the study — coworkers and colleagues. No significant effects were seen within those groups, which is interesting considering that some of us would interact with our co-workers upwards of 40 hours a week.

Prior to this study, researchers had determined that a person’s mood could immediately affect the mood of others, particularly by mimicking body language and facial expressions. A person could “catch” a mood in as little time as a few seconds, to as long as mimicking a roommate’s behaviors over several weeks.

Christakis’s study showed the significant role of social networks in happiness, referring to happiness as a “collective network phenomenon”, but one that decays over time and geographic distance. Within this network, Christakis found a relationship between an individual’s centrality and their level of happiness. Those who were on the periphery of their social network were more likely to be unhappy than those in the core.

With the World Health Organization (WHO) stressing happiness as an essential component of health, perhaps we should pay more attention to those we surround ourselves with in the hopes of catching more “good moods” than bad ones. Because, although there are several factors that aid in determining our happiness, people in our social network play a big role.


J. H Fowler, N. A Christakis (2008). Dynamic spread of happiness in a large social network: longitudinal analysis over 20 years in the Framingham Heart Study BMJ, 337 (dec04 2) DOI: 10.1136/bmj.a2338

Melissa E. Malka, BSc

Melissa E. Malka, BSc, holds a bachelors in Molecular Biology with a focus on neuropsychology, specifically the biology behind psychology. She is also pursuing a Masters degree and planning to attend medical school.
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