A study that monitored 4,700 over a period of 20 years found that a person’s neighbours’ or co-workers’ good spirits increased their level of happiness, which apparently spreads like a contagion among people.

The study, conducted by Dr. Nicholas A. Christakis, a physician and social scientist at Harvard Medical School, along with James H. Fowler, an associate professor of political science at University of California, San Diego, was published online Friday in the British medical journal BMJ.

Researchers’ findings showed that the choices and the actions of other people, even one, two and three degrees removed from a person could benefit their good mood, which is no longer a mission only for friends, life-partners and families.

Nevertheless, it seems that even happiness has a shelf-life, since one person’s joy can bounce another’s for as much as a year, so good news should really travel fast in order to have the desired effect.

The study found that a next-door neighbour’s happiness increased the chances of a person being happy  by 34 percent, but a down the block neighbour could do nothing to boost one’s mood.

Furthermore, a friend living one mile away made one’s joy go up by 42 percent, while one living two miles away could only bounce it by half that percentage. As for a friend from a different community, they could win the largest lottery jackpot and you wouldn’t feel even a bit happier.

According to Dr. Nicholas A. Christakis, this happens because in order for other people’s happiness to have an impact on another’s joy, physical and temporal proximity is a must.