Happiness is contagious, researchers reported on Thursday.
The same team that demonstrated obesity and smoking spread in networks has shown that the more happy people you know, the more likely you are yourself to be happy.
And getting connected to happy people improves a person's own happiness, they reported in the British Medical Journal.
"What we are dealing with is an emotional stampede," Nicholas Christakis, a professor of medical sociology at Harvard Medical School in Boston, said in a telephone interview.
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