ROME (Reuters Life!) - Americans are less happy today than they were 30 years ago thanks to longer working hours and a deterioration in the quality of their relationships with friends and neighbors, according to an Italian study.

A man covers his face at his desk in an undated file photo. Americans are less happy today than they were 30 years ago thanks to longer working hours and a deterioration in the quality of their relationships with friends and neighbors, according to an Italian study. REUTERS/Sergei Karpukhin

Researchers presenting their work at a conference on “policies for happiness” at Italy’s Siena University honed in on two major forces that boost happiness-- higher income and better social relationships -- and put a dollar value on them.

Based on that, they concluded a person with no friends or social relations with neighbors would have to earn $320,000 more each year than someone who did to enjoy the same level of happiness.

And while the average American paycheck had risen over the past 30 years, its happiness-boosting benefits were more than offset by a drop in the quality of relationships over the period.

“The main cause is a decline in the so-called social capital -- increased loneliness, increased perception of others as untrustworthy and unfair,” said Stefano Bartolini, one of the authors of the study.

“Social contacts have worsened, people have less and less relationships among neighbors, relatives and friends.”

He and two other Italian researchers looked at data from 1975 to 2004 collected by the annual General Social Surveys that monitors change in U.S. society through interviews with thousands of Americans.

By contrast, it appeared that based on the limited data available the happiness trend had remained largely stable in Europe, which had apparently avoided some of the changes in the American workplace like longer hours and more pressure.

“The increase in hours worked by Americans over the last 30 years has heavily affected their happiness because people who are more absorbed by work have less time and energy for relationships,” said Bartolini.

“Another important cause is that American society in the last 30 years has experienced a huge increase in competitive pressure compared to Europe. It’s easier in the United States, if you belong to the middle class, to become poor than you would in Europe. This creates a state of insecurity.”