According to the study, which was reported by CNN and published this week in the Journal of Occupational and Environmental Medicine, researchers found “significant changes” in the brains of individuals classified as overworked. The primary issues identified were excessive physical and emotional exhaustion combined with insufficient rest.

The South Korean Study

The research was conducted by two scholars from Chung-Ang University and Yonsei University in South Korea, involving 110 participants from the local healthcare system. The participants were split into two groups—those considered overworked and those with standard working hours. The study’s setting in South Korea is notable, as overwork has become a serious public health issue in the country, where the legal workweek can extend up to 52 hours.

The overworked group consisted of 32 individuals who worked at least 52 hours per week. These participants were, on average, younger, less experienced, and more highly educated than those in the control group who worked standard hours. Researchers compared data from prior studies and conducted brain MRI scans to analyze the participants' brain volumes using neuroimaging techniques.

This approach allowed them to detect and compare differences in the levels of gray matter in various brain regions. They also identified and labeled different anatomical structures in the scans. “Significant changes were found in brain regions related to executive function and emotional regulation among participants working 52 hours or more per week, compared to those with normal working hours,” the researchers stated.

Changes in Brain Anatomy

The areas where increased brain volume was detected include the posterior cingulate gyrus, which plays a critical role in cognitive functions such as focus, memory, and language processing, as well as the insula, involved in emotional processing, self-awareness, and social understanding.

The researchers believe their findings point to a potential link between increased workload and changes in these brain areas—offering a biological explanation for the cognitive and emotional difficulties often reported by overworked individuals. However, co-author Youn Yool Choi suggested that at least some of these changes might be reversible if environmental stressors are removed.

Broader Implications and Previous Findings

This study adds to a growing body of evidence highlighting the negative health impacts of long working hours. A 2021 joint report by the International Labour Organization (ILO) and the World Health Organization (WHO) estimated that overwork causes more than 745,000 deaths per year. Excessive work hours have also been linked to higher risks of diabetes in women and declines in cognitive function.

While the behavioral and psychological consequences of overwork are well-documented, the neurological and anatomical mechanisms have been less understood—until now. Frank Pega, one of the lead authors of the 2021 report, told CNN that the latest findings offer “new and important evidence” that can help clarify how excessive work hours drastically impact workers’ physical health. He did, however, caution that the relatively small sample size and the focus solely on healthcare workers in one country—South Korea—limit the generalizability of the results. “Further studies across more diverse populations are needed,” he said.

Still, Pega acknowledged the value of the research, suggesting it could help employees reduce their working hours based on scientific evidence. “The results highlight the importance of reducing working hours as a strategy to prevent health problems.”