A study has found that long working hours can alter the structure of the brain. It was revealed that this particularly affects brain regions responsible for executive functions such as emotion regulation, problem-solving, and memory.
Researchers from Chung-Ang University and Yonsei University published preliminary research in the international journal "Occupational and Environmental Medicine" on the 14th, stating that workers who work more than 52 hours a week show significant structural changes in specific areas of the brain compared to regular workers. Preliminary research refers to small-scale studies conducted before formal studies.
Excessive work is known to be associated with metabolic diseases such as cardiovascular diseases and diabetes, as well as mental health issues. The International Labour Organization (ILO) estimates that more than 800,000 people die from overwork worldwide each year. However, the specific effects of overwork on the brain and the changes it induces in brain structure have not been clearly established.
The research team analyzed brain magnetic resonance imaging (MRI) data from 110 medical workers using data from the Gachon Regional Occupational Cohort Study (GROCS). Among them, 32 individuals were in the overwork group working more than 52 hours a week, while 78 individuals maintained standard working hours.
The analysis revealed that the group which worked long hours had an approximately 19% increase in the gray matter volume of a brain region known as the "middle frontal gyrus". This area is responsible for complex cognitive functions such as attention, working memory, and language processing. Gray matter is densely populated with nerve cells. Additionally, the volume of the superior frontal gyrus, which is responsible for decision-making and planning, and the insula, important for emotion recognition and integration, also increased.
This study is a preliminary research based on short-term, small-scale data. Therefore, it is too early to determine a causal relationship between brain structural changes and overwork, whether the changes are a result of overwork or if pre-existing structural differences in the brain allow individuals to endure overwork. However, it is an important clue suggesting a relation between overwork and brain health.
The research team noted that "the increase in volume observed in the brains of overworked individuals may represent a kind of 'neural adaptation' as the brain tries to cope with chronic occupational stress," adding, "This could provide a biological basis for the cognitive or emotional difficulties that overworked individuals often experience." They further suggested that overwork should be treated not merely as a labor issue but as a health issue, indicating the need for policies to reduce long working hours.
References
Occupational and Environmental Medicine (2025), DOI: https://doi.org/10.1136/oemed-2025-110057