the new social network analysis showed that that contagious effect extends three "degrees" - as far as a friend of a friend of a friend - and drops off with time and distance. The effects can last a year, researchers said in British Medical Journal. "Your happiness is not just about your own choices and actions and behaviors and thoughts," said Dr. Nicholas Christakis, a coauthor of the study and a professor of medical sociology at Harvard Medical School. "It's like there are emotional stampedes that ripple across this infinite fabric of humanity." This new study looks at spouses, coworkers, siblings, neighbors, and friends. Using comprehensive data collected on 4,739 people over two decades, the researchers studied individuals' levels of happiness and their social relationships. A happy friend who lives within a mile, for example, boosts your odds of being happy by 25 percent, researchers found. A happy sibling within the same distance increases y...