Shift workers have lower thinking and memory scores, study shows.

If you seem to be working more than ever, it just might be because you are.

A new study comparing workdays in the United States with nearly 20 other European nations found this: Workers here put in about 25% more hours. American employees also are working more years before retiring.

The still-unpublished paper making these assertions was written by three economists: Alexander Bick, Ph.D., of Arizona State University, Tempe; Bettina Bruggemann, Ph.D., of McMaster University in Ontario; and Nicola Fuchs-Schundeln, Ph.D., of Goethe University Frankfurt, Frankfurt, Germany. They offered several possible explanations for the growing disparity.

One is that European workers typically pay higher income taxes and, therefore, might have a reduced incentive to spend more hours at their places of employment. Another possible explanation is that labor unions tend to be stronger overseas. Finally, it also may be possible that hard work may align more closely with higher pay and job promotion in the United States, they suggested.

Generous pensions in other nations may fuel earlier retirements, they added.

The workweek disparity is a relatively new phenomenon. European and American workers put in about the same amount of hours each week as recently as 1972, according to economists.