LONDON (AP) - A new study suggests happiness is contagious and that people pass on their good cheer even to total strangers.
The findings are in a paper being published Friday in the British medical journal BMJ.
American researchers who tracked more than 4,700 people in Framingham, Mass., as part of a 20-year heart study also found the transferred happiness is good for up to a year.
One of the study's authors says "Happiness is like a stampede." Happy people tended to be at the center of social networks and had many friends who were also happy.
Having friends or siblings nearby increased people's chances of being upbeat. Happiness spread outward by three degrees, to the friends of friends of friends.
Happy spouses helped, too, but not as much as happy friends of the same gender. Experts think people, particularly women, take emotional cues from people who look like them.