By Nathan Tucker 

A new study finds a direct correlation between working long hours and depression symptoms in first-year medical residents.

Research includes data from more than 17,000 first-year residents across the U.S. between 2009 and 2020. It found that average depression scores rose in tandem with the number of hours worked each week. One-third of residents who work more than 90 hours a week met the criteria for clinical depression, according to the report.

At the start, average scores indicated minimal depression symptoms; fewer than 1 in 20 met the criteria for moderate to severe depression. Researchers found that over the course of a year, residents' depression scores rose depending on how much they worked. Depression scores increased significantly for those working 90 or more hours, and just over 33 percent met the threshold for depression.

"There are just some parts of being a doctor that are going to be stressful, and you need breaks to allow yourself to recover," said Amy Bohnert, PhD, professor at the University of Michigan Medical School.

The Accreditation Council for Graduate Medical Education implemented rules limiting residents' work hours to 80 per week or 24 consecutive hours on duty. Further standards include that residents should not be on-call more than every third night and should have one day off per week.