Lessons from the world's longest study on happiness. n the 1930s, Harvard University began the longest study on human happiness:“What makes a good life?. Three lessons were learned from this (ongoing) study. When scientists began tracking the health of 268 Harvard sophomores in 1938 during the Great Depression, they hoped the longitudinal study would reveal clues to leading healthy and happy lives.“The surprising finding is that our relationships and how happy we are in our relationships has a powerful influence on our health,” said Robert Waldinger, director of the study, a psychiatrist at Massachusetts General Hospital and a professor of psychiatry at Harvard Medical School. “Taking care of your body is important, but tending to your relationships is a form of self-care too. That, I think, is the revelation.” Watch the revelations here.