Long work week may lead to mental decline

March 6, 2009 A new study suggests long work hours are linked to poorer performance on certain tests of cognitive function.

Compared with a group that worked 35 to 40 hours per week, those who worked 55 hours or more showed a greater decline in reasoning ability.

It's not clear whether the long work hours themselves explain the difference.

The study was conducted by researchers in Finland and is published in the American Journal of Epidemiology.