It's long been said that Misery loves company. And now there's scientific evidence to prove that statement as fact, thanks to a social networking study from James Fowler, a political scientist at University of Massachusetts, Framingham.

In Fowler's research, he took note of existing data from the Framingham Heart Study, which has recorded information on residents' health since 1948. The Heart Study primarily focuses on physical health, but also takes note of emotional data to study whether depression and heart disease have a connection. From the data, Fowler noticed that people in close proximity to one another showed similar emotional levels – in other words, happiness (or sadness) is contagious.

Next, he took the research a step further by logging onto Facebook and checking out the profiles of 1,700 students at a university. He found that the students who showed their pearly whites were likely to be connected to other smiling students, and the same was true for friends of friends. Likewise, those who bore surly expressions were likely to have similarly morose-looking friends on their own personal networks.

Fowler also found other commonalities within groups of friends within "three-degrees of influence," such as smoking and obesity. "The regularities are intriguing," he told Nature. "We think there are limits to how far influence can stretch, and we seem to be finding that across a broad range of phenomena."

So why not try your own experiment and smile at a stranger today? You never know how far they might pass it on.

By Kathryn Hawkins