Working 11 hours a day may not only make you more tired -- it could also make you more depressed.

A study of civil servants in England found that working excessive hours was linked with more cases of major depressive episodes. The 2,123 men and women observed in the study, published this week in the online journal PLoS One, were followed for an average 5.8 years and assessed for depression.

Working 11 or more hours a day was associated with a 2.3- to 2.5-fold increased risk of having a major depressive episode compared with those who worked a standard seven- to eight-hour day. That association held true after researchers adjusted for social and demographic factors, smoking, alcohol use and job strain.

The link between working very long hours and depression, researchers said, may be because of conflicts between work and family, problems winding down after the work day, and increased amounts of cortisol. Cortisol is a stress-related hormone that, when over-produced by the body, can cause health problems such as lower immunity and high blood pressure.


“Although occasionally working overtime may have benefits for the individual and society,” said lead author Marianna Virtanen in a news release, “it is important to recognize that working excessive hours is also associated with an increased risk of major depression.”