Americans “are in greater pain than citizens of other countries” and have been growing steadily more miserable for decades, according to a new working paper by David G. Blanchflower of Dartmouth College and Andrew Oswald of the University of Warwick.

For their paper, Blanchflower and Oswald investigate claims about happiness made by the Brookings Institution's Carol Graham in her recent book, “Happiness For All?". In the book, Graham draws primarily on Gallup data to argue American happiness is faltering as a rational response to growing inequality.

Among Graham's most striking finding is, as she puts it, “markers of well and ill-being, ranging from life satisfaction to stress, are more unequally shared across the rich and the poor in the U.S. than they are in Latin America, a region long known for high levels of inequality.” Low-income Americans are particularly skeptical that hard work will improve their economic situation.

Blanchflower and Oswald wanted to see if other data sources corroborated Graham's findings. They first turn to the General Social Survey (GSS), a nationally-representative survey administered every several years and used frequently in social science work.  The GSS data shows, unambiguously, that Americans' evaluations of their own happiness has been falling in recent years.

The decline is plainly visible across multiple demographic groups. Declines have been steepest among Americans with the least education, and the happiness gap between the most-educated and least-educated Americans has nearly doubled since 1972.

Blanchflower and Oswald note the GSS data shows similar trends for Americans' feelings about their finances — everyone is less optimistic about money relative to 1972, but optimism has dropped particularly sharply among the least-educated. They call these disparities a form of “psychological inequality,” which is both a reflection of actual monetary inequality and a driver of it — after all, it's difficult to improve your financial situation if you don't believe your financial situation can be improved.

As another marker of psychological distress, Blanchflower and Oswald look at cross-country data on the experience of pain. In 2011, the International Social Survey Programme asked respondents in over 30 nations how often they had experienced bodily aches and pains in the past month.

Americans were the most likely to report frequent pain, with 34 percent saying they experienced it “often” or “very often.” The average across all countries surveyed was just 20 percent.

“As the US is one of the richest countries in the world, and in principle might be expected to have one of the most comfortable lifestyles in the world, it seems strange — to put it at its mildest — that the nation should report such a lot of pain,” Blanchflower and Oswald write.

Aware that some of this could be attributable to question translation issues or cultural differences (for instance, Americans may just be more predisposed to complain about pain than members of other nations), the authors ran the numbers controlling for age, gender, marital status, labor force status and education. The United States remained an outlier even when these factors were accounted for.

The nation's relatively stingy social safety net may be one factor contributing to this exceptionalism. Many Americans still lack access to health care, which is available universally in most other wealthy nations. The expense of health care, even for those who have insurance, could mean Americans experiencing aches and pains are more likely to tough it out and forego treatment, relative to people in other countries.

In the United States, health issues remain a major contributor to financial insecurity, meaning they likely contribute to some of the declining happiness and financial pessimism seen in the other research surveyed by Blanchflower and Oswald.

All told, the data underscore how country-level material wealth can be a poor indicator for the well being of its inhabitants.