Harvard Study: Happiness Really Is Contagious

We've all had experiences where the sight of someone smiling makes us smile, the sound of laughter makes us laugh. Well, turns out that there's some science behind all that.

New research shows that happiness sets off a chain reaction. Nicholas co-authored a report released yesterday that's based on 20 years of data mined from the Framingham Heart Study, which has been going on since 1948.

Christakis is a professor of Medical Sociology at Harvard Medical School. He says his study shows that happiness is contagious.