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.


It also dawned on me that 1) happy people like to hang around other people (higher number of friends which increases their weight), and 2) happy people are thus more likely to have happy friends.
All this happiness stuff is strange.

Eric M. Jones

Deeply philosophical...dig around on and search "happiness". Some things you will learn:

1) Happiness seems inversely correlated to choices. The greater choices the less happiness.

2) There are sophisticated ways of capturing how happy people are. A study of emails saying "I feel happy" shows that Hawaii is the happiest state followed by Maine, Vermont, New Hampshire.....Remarkable.

But the cleanest non-Buddhist approach is Existentialism. Objective reality says nothing about happiness. The Subjective reality is where happiness dwells, and it can be manipulated from one minute to the next. If you want to be happy, then believing you are seems to do the trick.

So put on a happy face!


That second article is hilarious. Academiowned!


From the studies and things I've read, it absolutely makes good scientific sense. Here's why....

Neuro-linguistics lets us know that how we "talk" to ourselves impacts our behavior, attitudes, etc.

Further, we know that smiling actually makes you feel better/happier. Why? Very simply, the body is programmed such that when you smile, certain chemicals are released in response to that smile...making you feel better.

So, if you're around happy people, you are likely going to smile more often than around someone who is morose and the such.

Further, by smiling, you will feel better/happier, and your internal language is likely to improve, as well. You may go from "saying" to yourself, "I am such a loser," to, at the very least, being distracted from that negative message...and, at best, starting to speak/think in a very positive fashion to yourself (e.g., "Yes, I can make it! After all if Dubner and Levitt made it, it's a cinch that I can!").

So, yeah, it makes sense. A bit freaky and twisted, but, hey, we like that stuff, no?


Nathan Fiala

One of the authors of the happiness study, James Fowler, has a "pile" of research that suffers from similar problems. He supposedly proved the Colbert bump, though again its only correlational (what if politicians go on Colbert right before campaigning?). He also has two other papers using the Framingham Heart Study data on obesity and smoking that are likewise useless. How do researchers get away with publishing these kinds of results?

W Fred

What mystifies me about the Fowler-Christakis happiness study is that they found no effect among coworkers, a mild effect among coresident spouses, and a stronger effect among next-door neighbors. whiskey tango foxtrot! You'd think the opportunity for "contagion" would be greater in the home and the workplace. The authors' explanatory hypotheses (for the spouse finding, that you're more likely to pick up happiness cues from people of the same gender, and for the coworker finding, that perhaps there are other things going on in the workplace-- because of the competitive nature of the workplace, says Fowler, according to one of the press accounts-- that might counteract the contagion) are unpersuasive. That said, though, I think there's something intriguing here-- but it needs to be further verified.


Thank you for calling correlation on contextual effects. The authors seem to argue that mood shapes context but that is backwards. Given that we have context (self-selection, etc.), it would seem that mood is more a consequence of context.

The real lesson would be: hang out with happy people if you want to be happy. Hang out with successful people if you want ...

And that, of course, fits with our human experience: we worry about our kids hanging out with the loser crowd, with the "bad" kids who are "bad influence."


The "similar influenes" causation seems most likely. I'm fairly sure that $5,000 cash would cause more happiness in me than my friend's friend having a good day.


Entirely unscientific and anecdotal support for the study's conclusion: I am an introvert and a curmudgeon. I enjoy being around happy-go-lucky people. They make me feel less Eeyore-like. Indeed, their happiness is, well, contagious.

That said, I'm sure there are many curmudgeons that would rather be alone all the time.


GREAT article. That made me happy.


Now that my skeptic hat is on, though, it should be pointed out that Cohen-Cole and Fletcher measure reported heights, headaches, and acne. The former is likely to be fairly objective, and by itself is probably dispositive. The latter two could, however, be plausibly "contagious," inasmuch as both the psychological perception of, and reports to doctors of, headaches and acne might indeed be affected by others around you complaining of the same thing. I've certainly known people who were great complainers about headaches and caused those around them to notice aches they might otherwise have ignored. As as for acne, the self-consciousness felt by those with mild acne is highly affected by what those around them are saying -- just go to an acne self-help website and see. So though I agree with their conclusions, the debunkers should have chosen two additional variables more like height to fill out their study, since otherwise the true skeptics might dismiss both Fowler's and their studies and say, well, that's the nature of statistics -- I still don't know anything one way or the other.


Mike M

I'll admit to not having looked at the details of the study.

I a few things to mention:

Merely thinking of most of the people on my Facebook friends list tend to make me happy. Most of them are from college, and we had some great times.

Could those associations have cued a responce in those taking part in the survey?

Also, is there a positive correlation between college graduates and happiness, perhaps even a causal relationship?

Again, I don't know how the study was administered. You'd think they'd control for those types of things, but given the "explanations" for co-workers, spouses and neighbors it would not surprise me if these things were not properly considered.


I heard a scientific proof and have experienced myself that the meal one has is not only determined by the quality of it (product used), the presentation of the food, the taste is actually greatly affected by the environment - that is, whom s/he is having the meal with. Others saying how the food is delicious, which make the individual's neuron to fire - “yummy” signals (in addition to the smell and other stimulus) to the brain - thereby making the person enjoy the food more than the actual response. Hence, surrounding people - environment - affects others. This is particularly true about happiness - happiness IS contagious! Everybody likes and wants to be happy, rather than miserable, and angry. People who are “jolly” are popular or liked by the majority. They would usually say nice things about other which make the person happy which gives him an extra “margin” to be kind to others, do them a favour. This is a cycle that keeps going on. Hence “happiness” is contagious as it keeps repeating.



Economists dismiss social influence as a cause because they ignore causal studies in psychology. The issue isn't if social influence is a cause, because decades of behavioral experiments show it is. The real issue is if the effect size is great enough that happiness spreads in a major way outside the lab. Clearly, the stochastic model in the C&F study has flaws, but so do the vast majority of observational studies that use panel data instead of experiments.

The author cites interdependent sampling as an alternative explanation to social influence, when I see it as a type of social influence.

My question is, why don't economists use their considerable modeling skills to address social influence head on, controlling for it with models, instead of irrationally pretending it doesn't exist!


Why don't you let your readers know that the authors of the original study (Fowler and Christakis) have responded quite ably to the concerns raised by Cohen-Cole and Fletcher? They have a supplement to the happiness study that discusses some of these issues available here:

Also, this isn't the first time that Cohen-Cole and Fletcher have been critical of Fowler and Christakis; the authors put together a response to that previous criticism as well, which can be found here:

I'm surprised that t one of the authors contact this blog and ask that you make your readers aware of these responses... or did they?


response to NCProsecutor

As outlined in this response, the Fowler and Christakis paper in the JHE has several problems:

Leigh Caldwell

In response to this highly dubious result (and I include Wolfers and Stevenson's article of August 4th in that) I have carried out some related research in the following article: Coolness Inequality Declines. The counterintuitive result is that American society is much cooler today than in the 1960s and that inequality in coolness has been substantially reduced.

"...using self-reported happiness to measure actual happiness is no more valid than using self-reported sexual activity to measure the birth rate."

Talk Turkey

As I posted on my blog, my own conclusions lead me to believe that happiness is contagious, and the only known cure is to associate with 'unhappy' social contacts. Practice caution when doing so, and always wear protection. A smile on your face might fend off those not willing to participate in your positivity and need for mutual gratification.

I wonder if there will ever be a study worth millions of dollars that proclaim positivity and happiness are interrelated...


I'm not completely decided on whether happiness is contagious or merely a result of environmental factors,but I do know it is one of the factors of life that can not be priced. Though economics is about the flow of money, I find that the things that hold the greatest values are the ones that are "priceless", as cheesy as that sounds.
Hence, when considering implicit costs in everyday decisions, happiness is one of the largest factors because in essence it is what we pursue in life. Taking up a job that will make you a millionaire but requiring long hours of unattractive work may not be the answer. Though it would be the most '"efficient answer" because of the large profits, people would not choose it because what's the point having money when you have to spend your life doing something you hate. So whether happiness is contagious I am unsure, but I do know it is the most valuable implicit cost we'll ever come across.



THANK YOU! I was seething after I saw the NYT article and Today show piece. The paper is clearly flawed and this point deserves attention, especially when a very good falsification exercise exists WITHIN THE SAME ISSUE OF THE SAME JOURNAL.

I don't doubt the existence of a Mary Poppins phenomenon: happy people do make others happy. At the same time, if peer effects are indeed overstated, we should be careful in ascribing too much importance to "social multiplier" effects when justifying public programs.