Is Happiness Contagious?

If those riding intellectual fads are sometimes guilty of sloppy reasoning, imagine what happens when two fads collide.

That’s what happened when the British Medical Journal elected to publish a study analyzing 1) happiness in 2) social networks. The study, by James Fowler and Nicholas Christakis, concludes that happiness is contagious within social networks.

According to the authors, your happiness depends on the happiness of your friends, and their friends, and their friends. It’s a fascinating finding, and it was duly reported by hundreds of newspapers. Indeed, according to Fowler, “if your friend’s friend’s friend becomes happy, that has a bigger impact on you being happy than putting an extra $5,000 in your pocket.”

Unfortunately, it’s probably not true. Here’s the crux of the research: the authors show that your happiness is positively related to the happiness of your friends, and that this holds even after accounting for a number of other variables, including how happy you and your friends were a few years back. That’s correlation; what about causation?

There are (at least) three reasons why happiness is correlated within social networks. It may be that — as the authors posit — happiness is contagious. Or perhaps people with similar dispositions are more likely to be friends. Economists call this the confounder “selection effects,” while medical journals call it “homophily.” The authors partly account for this by adding statistical controls for the past happiness of both you and your friends.

The third reason is perhaps the most likely: if you and I are friends, we are often subject to similar influences. If a buddy of ours dies, we’ll both be less happy. Or, less dramatically, if our favorite football team wins, we’ll both be happier. But this isn’t contagious happiness — it is simply a natural outcome of the shared experiences of people in the same social circles. Unfortunately, observational data cannot distinguish the headline-grabbing conclusion — that happiness is contagious — from my more mundane alternative: friends have shared emotional influences.

Interestingly, the same issue of the BMJ contained a very careful article by Ethan Cohen-Cole and Jason Fletcher making precisely this point. They employ a pretty cheeky research strategy: if you want to show that a research design is silly, show that it leads to silly conclusions.

They use Fowler and Christakis’s approach on another dataset, and show that it leads to the unlikely conclusion that height, headaches, and acne are also contagious. The more likely explanation, of course, is that all are subject to similar environmental influences. For instance, the same jackhammer causing your headache is likely causing mine.

I bet that a similar analysis would show that stories about happiness being contagious are, well, contagious. After all, what else explains last week’s epidemic, with stories in The New York Times; The Boston Globe, and The Washington Post? Of course, it may just be that this “epidemic” reflects a shared environmental influence, like each newspaper receiving the same press release.

So we have two studies drawing two conclusions. The first finds that happiness is contagious; the second finds that researchers can too easily draw false conclusions about contagion. Guess which one grabbed the attention of headline writers.


You know, before you upbraid the press for not looking into things enough, you should really look into things yourself. The issues between these two sets of researchers are pretty subtle, and even the experts are really not sure how this debate will settle out over time. The NY Times story on the happiness research did mention the methodological questions, pretty high up in the article, as did many others. That seems to me to be pretty responsible press coverage.

For the real story, see

Tom Robischon

Neither the Times, Post nor Globe (nor the L.A. Times) included in their stories on the Fowler-Çhristakis study that they found the influence of spouses was next to lowest among the various social networks. "Sex also plays a part in the spread of happiness," their report said. "Happiness spreads significantly more through same sex relationships than opposite sex relationships . . . possibly helping to explain why friends and next door neighbours might exhibit stronger effects than spouses (who in our sample were all opposite sex). . . . people might be more likely to take emotional cues from members of the same sex."

When I asked Prof. Christakis whether this meant same-sex marriages might be happier than opposite-sex, he said he wouldn't be surprised if it did, and he wouldn't be surprised if it didn't.

Wow! Do proponents of same-sex marriages know about this?

Tom Robischon

Oops. My previous post was mistaken. The Boston Globe did mention the low influence of spouses, and the same-sex theory, but it didn't go beyond that.


Here is a question for you, do people laugh more if others around them laugh.

Is laughter a social response that you do only when others are present as a means of communicating pleasure/amusement?

Y. Kang

It must be so as in the following:

(1) VALID HAPPINESS (including love, sense of beauty, symbiosis (good conscience, upholding justice, moral couraging, helping others, teaching…) bravery, etc.) must be the feeling of things being a step better for our propagation.
(2) WELL-BEING is the ongoing feeling of things going well step by step for our propagation.
(3) VALID SUFFERING must be the feeling of things being harmful to our propagation and calling us to prevent or rectify it.
(4) SOUL (including: personality, inspiration, etc.) is the computation results of both our instinct and pre-instinct data-programs in our brain.
(5) LIFE GOAL is to propagate.

All these are our instincts (ancestors' successful experiences saved on DNA).



Happiness is contagious

Gregory S. Barsh, Esq.


ruHap, The Happiness Company released yesterday the first-ever Facebook application designed to spread Happiness through social networks.

It is available to Faccebook users at

Based on the Framingham Heart Study research, users post whether they are Happy or not thus helping their friends be Happier, and their friends, and their friends too. ruHap collects the votes and publish a daily Happiness Index.

The Happiness app is linked to our free website which contains extensive Happiness Resources, a Daily Happiness Quote, a blog (How to be Happy) and much more. ruhap brings the leading academic Happiness research to users in small, fun, bite sized pieces.

Thank you very much, and Be Happy,

Gregory S. Barsh, Esq.
Chief Happiness Officer
ruHap, The Happiness Company