Working long hours each week may do more than leave you tired — it could actually change the structure of your brain, according to a new study from South Korea.
Researchers from Chung-Ang University and Yonsei University found what they described as “significant changes” in the brains of health workers who regularly logged 52 hours or more per week.
The peer-reviewed study, published in Occupational and Environmental Medicine, suggests that overwork may not just impact mental well-being but could actually alter brain regions linked to memory, emotional control, and decision-making.
The study analyzed 110 health workers, dividing them into two groups: 32 who worked long hours and 78 who maintained standard schedules. Using advanced MRI scanning techniques — including voxel-based morphometry (VBM) and atlas-based analysis — scientists discovered that those in the overworked group showed increased volume in areas of the brain associated with executive function and emotional regulation.
One specific finding was a 19% increase in the volume of the middle frontal gyrus — a part of the frontal lobe that plays a key role in attention, language, and working memory. Other affected regions included the superior frontal gyrus and the insula, both of which are critical for planning, self-awareness, and interpreting emotional cues.
The researchers believe these physical changes may explain the cognitive fog, irritability, and mental exhaustion commonly reported by people who feel overwhelmed by their workload. While the study stops short of proving cause and effect, it offers a biological basis for symptoms many workers have long described.
“These increased brain volumes may reflect neuroadaptive responses to chronic occupational stress,” the study authors said. “However, the exact mechanisms remain speculative.” They called for further research using long-term data to confirm the findings and explore whether these changes are reversible or long-lasting.
The potential consequences aren’t limited to individual health. Experts say the results highlight a broader issue with modern work culture, especially as technology blurs the line between office hours and personal time.
Ruth Wilkinson of the Institution of Occupational Safety and Health in the UK warned of “an epidemic of long working hours,” fueled by unwritten expectations to stay available outside of official shifts. “It includes always having to be available/on duty in this digital age, stripped of the right to disconnect from work,” she said.
The International Labor Organization estimates that overwork contributes to more than 800,000 deaths globally each year, mostly from heart disease and stroke. But this study suggests the toll may also extend to subtle — but real — changes in brain anatomy.
As the American workforce continues to age, and many workers feel pressure to delay retirement or increase productivity, this research could inform workplace policies aimed at protecting long-term cognitive health.
The study authors concluded with a warning: “The results underscore the importance of addressing overwork as an occupational health concern and highlight the need for workplace policies that mitigate excessive working hours.”