New research from Harvard Medical School and the University of California, San Diego suggests that happiness is influenced not only by the people you know, but by the people they know.
The study showed that happiness spreads through social networks, sort of like a virus, meaning that your happiness could influence the happiness of someone you’ve never even met.
They concluded that the happiness of an immediate social contact increased an individual’s chances of becoming happy by 15%, Fowler says.
Having more friends also increased happiness, but having friends who were happy was a much bigger influence on happiness.
Article - Social Networks Affect Mood, Study Shows By Salynn Boyles WebMD Health News
Dec. 4, 2008 — Could happiness be contagious?