(LONDON) -- Work can be depressing at times -- that much most people know -- but now, a European study suggests that those who work long hours are twice as likely to experience a major depressive episode.
In a report published in the Jan. 25 online journal Plos ONE, researchers at the Finnish Institute of Occupational Health and at University College in London followed 2,000 middle-aged government workers in Britain and saw a link between overtime work and depression. They found that those working more than 11 hours a day were at the greatest risk.
The study was adjusted for other variables, such as socioeconomic backgrounds, lifestyle and other work-related factors.
Another study of the same group last year found a 67 percent higher risk of coronary heart disease. Study authors conceded results might have been different had they studied a younger age group.
"It is true that depression is more common in middle age, and it might also be possible that in order to have any effect on health, quite a long period of exposure to long hours is needed," author Marianna Virtanen told ABC News in an email.
Her advice to American workers was to, "make a distinction between work and leisure; don't skip your holidays; take care of your health and well-being, especially sleep and exercise."
The average number of hours worked annually by employees in the United States has steadily increased, according to the Centers for Disease Control (CDC) and Prevention's 2004 report, "Overtime and Extended Work Shifts."
American workers now surpass Japan and most of Western Europe in the number of hours devoted to working, the CDC reported.
Copyright 2012 ABC News Radio