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In largest study of its kind, CU-Boulder researchers find that happiness is its own reward. Why, exactly, this is true remains a mystery.

Some peer-reviewed studies have found that happy people tend to live longer than their less-happy counterparts. But now, for the first time, researchers have found that happiness all by itself—regardless of marital status, income, physical health and other indicators—is a key factor in longevity.

“There has been so much focus on what makes people happy,” says Tim Wadsworth, associate professor of sociology at the University of Colorado Boulder. “But we asked what are the outcomes of happiness, and in some sense, being happy is an outcome of its own.”

The study was published in the journal  this fall. Wadsworth’s team included Elizabeth M. Lawrence at the University of North Carolina-Chapel Hill and Professor Richard G. Rogers of the CU-Boulder Department of Sociology. The team’s work was based on a far broader sample than previous studies.

Previous studies regarding happiness and longevity have been smaller or more narrowly focused. The classic “nun study,” for example, examined the writings of a few hundred nuns from the time they entered a convent until their deaths.

“That study found that those that wrote stories that were coded as demonstrating a happier disposition tended to live longer. This study, and others like it, were getting at the same argument we are getting at, but they weren’t a nationally representative sample,” Wadsworth says.

Using nationally representative data from the General Social Survey between 1978 and 2002, the new study examined more than 32,000 individuals, how long they lived and their responses to questions about their happiness and a variety of other characteristics. As such, the researchers were able to control for such well-established correlates of both happiness and longevity as education, marital status, race and income.

The researchers found that the risk of death for unhappy people is 14 percent higher than those who are “pretty happy,” whose risk is 6 percent higher than those described as “very happy.”

“Further, we found no significant interactions between happiness and the other covariates,” they concluded. “That is, mortality risk is lower for happy than unhappy individuals, and for married than unmarried individuals, but there is no additional longevity benefit for people who are both happy and married.”

In other words, they found that happiness is a stand-alone indicator of well-being and longer life.

“But here’s the caveat,” Wadworth says. “We don’t really know why. We are very confident there is a correlation, but cannot claim this is causal at this point. We can’t claim that happiness guarantees a long life.”

Wadsworth has also been looking into rates of happiness between different ethnic groups in America. African Americans and Asian Americans report much lower levels of happiness than their white counterparts (Hispanics are harder to gauge, since they cross racial boundaries).

But where most of the variation can be explained by socio-economic factors, Asian Americans seem to be an outlier, he says. Even after controlling for a variety of factors Asian Americans still report much lower levels of life satisfaction.

At a broad level, a human tendency to compare our circumstances with those of others living around us may provide a clue. Studies have found, for example, that obesity is more detrimental to life satisfaction when obese people are living around non-obese people.

“In geographic areas where there are lots of fat people,” Wadsworth says, “obesity has little effect on life satisfaction.”

Ditto for marriage: Studies consistently find married people are happier than their unwed counterparts, but the effect is amplified for married people living in communities where there are high rates of marriage.

Well-being and happiness, in other words, are linked to expectations.

“What is your reference group? What are your expectations?” Wadsworth asks. “There is a fair amount of research that a disconnect between what (people) want life to be like and what it is actually like can determine how happy they are.”

Wadsworth says the findings in the recent paper point to a need for a more-interdisciplinary approach to delve further into the relationship between happiness and longevity and gain a better understanding of the processes behind the data.

“Maybe the key question is not just how to be happy, but what are the consequence of being happy,” he says.

Clay Evans is a free-lance writer and longtime Boulder journalist.