happiness can be contagious

Happiness can be contagious, even happiness from strangers. so how about an idea of happiness social network?

From New York Times:

How happy you are may depend on how happy your friends’ friends’ friends are, even if you don’t know them at all.

And a cheery next-door neighbor has more effect on your happiness than your spouse’s mood.

So says a new study that followed a large group of people for 20 years — happiness is more contagious than previously thought.