Preliminary research published in Occupational & Environmental Medicine suggests that long working hours may physically alter the brain’s structure, particularly in regions responsible for emotional regulation and executive functions such as working memory and problem-solving. The study, which utilised advanced neuroimaging techniques, observed notable differences in the brain anatomy of individuals routinely working 52 hours or more per week compared to those working standard hours. According to the researchers, these structural changes may reflect the brain’s neuroadaptive response to chronic occupational stress, potentially influencing cognitive and emotional health over time.
The consequences of overwork have long been associated with a heightened risk of cardiovascular disease, metabolic disorders, and a spectrum of mental health issues. Data from the International Labour Organisation estimates that excessive working hours contribute to more than 800,000 deaths globally each year. While overwork’s psychological and behavioural implications are well-documented, its neurological and anatomical impact remains an underexplored frontier. To address this knowledge gap, researchers analysed structural brain volume in a cohort of South Korean healthcare workers using MRI data collected as part of the Gachon Regional Occupational Cohort Study (GROCS).
The study involved 110 participants, most of whom were clinicians. They were divided into two groups based on working hours: 32 individuals were classified as working excessive hours, while 78 fell within the standard work range. Interestingly, those in the overworked category were generally younger, had fewer years of professional experience, and possessed higher levels of education. This demographic distinction, however, did not account for the neuroanatomical differences observed, suggesting that the prolonged duration of work itself may play a significant role in shaping brain structure.
To assess these differences, the researchers employed voxel-based morphometry (VBM) and atlas-based analysis—two sophisticated neuroimaging methods that precisely compare grey matter volume and identify anatomical regions. Their analysis revealed that individuals working longer hours significantly increased brain volume in areas associated with executive control and emotional processing. Notably, a 19% increase in the volume of the middle frontal gyrus was identified, a region involved in attention regulation, working memory, and higher-order cognitive functions. Additional increases were noted in the superior frontal gyrus, which governs planning and decision-making, and the insula, which integrates sensory and emotional input and is central to self-awareness.
While the researchers acknowledge the limitations of their study—chief among them its small sample size and observational design—they argue that these findings present a meaningful foundation for further inquiry. Without long-term data, whether the observed brain changes directly result from overwork or represent pre-existing anatomical differences predisposing specific individuals to tolerate or seek out longer hours remains unclear. The increased brain volumes could indicate a form of adaptation to chronic stress, although the mechanisms underlying this remain largely speculative.
The authors conclude by underscoring the broader implications of their findings. These changes in brain structure could provide a biological explanation for the cognitive and emotional difficulties frequently reported by individuals subjected to prolonged occupational stress. They call for expanded research efforts, particularly longitudinal and multi-modal neuroimaging studies, to validate these initial observations and delve deeper into the causal relationships. Most importantly, they emphasise the urgent need to treat overwork as a significant occupational health issue, advocating for workplace policies that actively discourage excessive working hours and prioritise employees’ mental and neurological well-being.
More information: Wonpil Jang et al, Overwork and changes in brain structure: a pilot study, Occupational and Environmental Medicine. DOI: 10.1136/oemed-2025-110057
Journal information: Occupational and Environmental Medicine Provided by BMJ Group
