While a lack of credentials doesn't exactly have a positive effect on job prospects, a college education may be the path to a long, arduous workweek for professional careers.

A study done for the National Bureau of Economic Research by economists Peter Kuhn of the University of California at Santa Barbara and Fernando Lozano of Pomona College highlights some trends in the length of the workweek.

Most notably, they found that highly educated and salaried male professionals have been working more 50-hour workweeks since 1970, reversing the trend of a declining workweek in the earlier part of the century.

Lozano and Kuhn concluded that employees are expecting -- and getting -- more out of their highly skilled employees.

"Americans work longer hours than virtually any country in the world," said Paul Clark, a professor of labor studies and industrial relations.

Clark said that longer workweeks could be a factor contributing to the strength of the American economy and that expectations of employers in the United States may be higher.

Clark added that too much work could be a bad thing.

Sometimes people don't consider the costs to their health and family relationships, he said.

"When fathers work long hours, they have less positive relationships with their children, but only when they feel overloaded," said Ann Crouter of the Center for Work and Family Research, a division of Penn State's College of the Liberal Arts.

Crouter and three other researchers authored a study that concluded that American companies need to offer more jobs that do not make their employees work long hours but still provide large enough salaries to support a family.

According to their study in The Journal of Marriage and Family, "Employers need to develop strategies to reduce employees' feelings of overload."

Highly educated people seem to be fitting less recreation time into their lives than the less educated as well. People older than 25 with less than a high school diploma spend 1.8 hours more per day engaging in leisure activities than do those with a bachelor's degree or higher, according to the 2005 American Time Use Survey by the U.S. Department of Labor.

People have less time to do stress-reducing recreational activities as more of their time is consumed by work, said Sonia Cavigelli, assistant professor of biobehavioral health. She added that there is a great deal of information about what causes physical and psychological stress, but not as much about coping with it.

"Exercise and meditation are some of the best coping mechanisms we know about," Cavigelli said.

According to a report released by the National Science Foundation (NSF), people who hold doctorates in their fields are working more than most Americans.

The NSF study found that those who had doctorates and worked in the education field clocked about 50.6 work hours a week, followed by those in industry or self-employment at 47.6 hours and government workers at 45.2 hours a week.

In the education field, instructors who are on tenure track but are not yet tenured worked the longest weeks -- 52.5 hours.