More hours at work = greater risk of depression, study shows

By Stephen Beech via SWNS

The more hours people work each week in a stressful job, the greater their risk of depression rises, according to a new study of junior doctors.

Working 90 or more hours a week saw changes in depression symptom scores three times larger than the change in depression symptoms among those working 40 to 45 hours a week.

And a higher percentage of those who worked many hours had scores high enough to qualify for a diagnosis of moderate to severe depression - serious enough to warrant treatment - compared with those working fewer hours.

The University of Michigan team used advanced statistical methods to emulate a randomized clinical trial, accounting for many other factors in the doctors’ personal and professional lives.

They found a “dose-response” effect between hours worked and depression symptoms, with an average symptom increase of 1.8 points on a standard scale for those working 40 to 45 hours, ranging up to 5.2 points for those working more than 90 hours.

They conclude that, among all the stressors affecting physicians, working a large number of hours is a major contributor to depression.

The team studied 11 years’ worth of data on more than 17,000 first-year medical residents. The recently graduated doctors were training at hundreds of hospitals across the United States.

The data come from the Intern Health Study which each year recruits new medical school graduates to take part in 12 months of tracking their depressive symptoms, work hours, sleep and more while they complete the first year of residency, also called the intern year.

The most common work hour levels were between 65 to 80 hours per week for the doctors in the study.

The Accreditation Council for Graduate Medical Education (ACGME), which sets national standards in the US for residency programs, currently sets an 80-hour limit on residents’ work weeks, but that can be averaged over four weeks and there are possible exceptions.

ACGME also limits the length of a single shift and the number of days residents can work in a row.

However, the research team said their findings point to a clear need to further reduce the number of hours residents work each week on average.

Study senior author Professor Amy Bohnert, of the University of Michigan Medical School, said: “This analysis suggests strongly that reducing the average number of work hours would make a difference in the degree to which interns’ depressive symptoms increase over time, and reduce the number who develop diagnosable depression.

“The key thing is to have people work fewer hours; you can more effectively deal with the stresses or frustrations of your job when you have more time to recover.”

Study lead author Yu Fang, noted that the number of hours is important, but so are the training opportunities that come from time spent in hospitals and clinics.

She said: “It is important to use the time spent at work for supervised learning opportunities, and not low-value clinical service tasks study."

Intern Health Study founder Professor Srijan Sen said new physicians entering the most stressful year of their careers make a "perfect group" in which to study the role of many factors in the risk or onset of depression.

He said that similar studies should be conducted in other high-stress and high-work-hour jobs, adding: “We would expect that the negative effect of long work hours on physician mental health would be present in other professions."

The average age of the doctors in the study was 27, and just over half were women.

Less than one in 20 met the criteria for moderate to severe depression at the start of their intern year.

In all, 46 percent had a stressful life event such as a family death or birth, or getting married, during their intern year, while 37 percent said they had been involved in at least one medical error during the year.

Prof Sen added: “This paper demonstrates how big of an impact that the single factor of work hours has on clinician depression and well-being.”

The findings were published in the New England Journal of Medicine.