Working 11 hours or more a day linked to depression

By Dr. Ananya Mandal, MDJan 29 2012

New research suggests that working for 11 hours or more a day may not only tire an individual but also raise the risk of depression.

The study included civil servants in England and showed 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. The majority of the study participants (52%) worked a normal seven- or eight-hour workday. Thirty-seven percent averaged nine- or 10-hour days, and 11% worked 11 hours or more.

Overworked junior and mid-level employees appear to be more prone to depression than people higher up the food chain, the study suggests. The length of the workday didn't have a perceptible impact on the mental health of higher-paid, top-level employees such as cabinet secretaries, directors, team leaders, and policy managers.

The researchers found that 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 problem they found could 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.”

Although the findings are “consistent with previous studies, the degree of increased risk was surprising,” says Bryan Bruno, chair of the psychiatry department at Lenox Hill Hospital, in New York City, who was not involved in the research. “The biggest condition that I work with is depression, and it is often related to work stressors.” Job insecurity and sleep deprivation also may help explain the increased risk of depression, Bruno says, noting that previous research has shown that poor sleep is a key ingredient in work-related depression. “I often really focus on that symptom,” he says, referring to his own patients.

The study had several shortcomings write the authors. The authors looked only at white-collar civil servants, for example, so it's not clear whether the results would apply to blue-collar workers or to employees in the private sector. Another question the study doesn't answer is how long an employee can maintain 11-hour workdays before the risk of depression begins to rise.