There are many factors involved in making someone happy, but how important is the happiness of those around us: our family, friends, neighbors, co-workers?  Does happiness rub off? Is happiness contagious?

You might have your own answers to those questions, but they're probably very experiential and very unscientific. After all, happiness is difficult to study: Its abstract nature makes it hard to quantify or measure. So it was surprising to see an article in the latest edition of the British Medical Journal take a stab at understanding the dynamics of this most elusive of feelings.

The authors of the study used data from the Framingham Heart Study (an ongoing, three-generation study that began in 1948 in a Boston suburb of the same name) to generate what you might call a "posse-gram," a three-dimensional representation of the social networks — friends, co-workers, neighbors, family — of nearly 5,000 study participants. Using data from depression questionnaires participants had filled out as part of the study, the researchers were able to follow how the sense of happiness moved throughout these large social networks over time.

Adding "happy" or "unhappy" colors to these social network diagrams made it easy to draw some conclusions: Happy people tended to cluster together, and were more often found in the central core of the social network, where they were plugged into more people in more directions. Unhappy tended to be on the periphery, with fewer social lines connecting them to the center.

So happy people tend to cluster together — not surprising — but the challenge for the researchers was to use statistical analysis to try to tell why that was the case. Do people who are happy cluster together because like attracts like (known as "homophily"), or is happiness something that can be transmitted (termed "induction")?

It turns out that happiness is contagious. It moves dynamically through social networks, and here are a few key findings:

The power to transmit happiness weakens over the chain of friendship.
If I become happy, and I'm friends with Jane, she's 15 percent more likely to become happy. And if Jane is friends with Chuck (but I don't know Chuck), then Chuck is about 10 percent more likely to be happy because of the spillover happiness effect I share with Jane. And a friend of Chuck's is 5.6  percent more likely to be happy because of his link to me, Mr. Happy. But that's it: four friends — three degrees of separation — and then the smiley power fades to, yes, black.

The power to transmit happiness weakens with geographical distance.
You'll be 42 percent more likely to be happy if a friend who lives less than a half a mile away gets happy, but only 22 percent more likely if that friend lives between 0.5-2 miles away.

Proximity can outweigh bloodlines.
Friends might be more important than family. A sibling who lives within a mile and becomes happy increases your chances of becoming happy by 14 percent. But a next-door neighbor who becomes happy increases your chance of being happy by 34 percent (OK, so these researchers have never met your neighbors). One exception to the proximity rule: Co-workers didn't seem to have any influence on happiness.

If your neighbor could have such an effect on your happiness, then what about a spouse — the "soulmate," "the old-ball-and-chain" (both of which imply a geographically close relationship)? Surprisingly, a spouse becoming happy increases the probability that his or her spouse will become happy by a mere 8 percent. What could possibly explain that?

Curiously, these researchers found that happiness seemed to spread more effectively through same-sex relationships than through opposite-sex relationships. Odd to consider, really, but my happiness might be more dependent on how my guy friends are than how my wife is feeling. The article doesn't address the reason for this specifically, but it does point out that happiness is spread, in part, by social mimicry, and that it's well established that humans are more likely to take emotional cues from members of the same sex.

The good news is that happiness is more powerful than unhappiness. If you had just two friends in the world, Eeyore and Tigger, then Tigger would have a more powerful impact on your mood. That's the wonderful thing about Tiggers …

So as we slide into the darkness of winter and into the holidays (when intense psychosocial pressures and unrealistic expectations have the ability to compress a diamond into a lump of coal), remember that happiness isn't just a solo sport. Sure, you might be able to pull yourself up by your bootstraps, but you'll have better luck if those who are emotionally and geographically closest to you are happy and around to lend you a hand — and a smile or a joke.