Happiness is contagious in social networks

Source: CNN; British Medical Journal, December 2008

A longitudinal study that analyzed the effects of social networks from 1983 to 2003 found that happiness is contagious among friends up to three degrees removed. That is, a person is 15 percent more likely to be happy if a direct friend is happy, 10 percent if the friend of a friend is happy, and six percent if a friend of a friend of a friend is happy.

Sadness, however, does not spread quickly among friends. The study also found that geographic proximity also can impact happiness. Friends who live within a mile from each other increase one’s probability for happiness by 25 percent. Similar effects were found between spouses, siblings and neighbors (but not among co-workers).

The authors used self-reported happiness ratings from the Framingham Heart Study and recreated a network of 4,739 friends, spouses and siblings. They concluded that social relationships are a top predictor for human happiness and that a large network of friends increases one’s likelihood of being happy.