Long Workdays Quietly Rewiring The Brain
Working extended hours has been recognized as a serious health risk, with the World Health Organization (WHO) attributing 745,000 deaths from stroke and heart disease in a single year to this factor. While the link between overwork and adverse health outcomes is well-documented, the biological mechanisms remain somewhat mysterious. However, recent research may help clarify this, as it found that prolonged working hours are associated with changes in brain structure—specifically, increases in the size of multiple brain regions. These alterations may be responsible for the cognitive and emotional difficulties often observed in individuals who consistently work beyond the standard 40-hour week.
This study supports prior findings that associate long working hours with a heightened risk of physical health problems, including cardiovascular disease, and emphasizes the importance of maintaining a healthy work-life balance. In the research sample, 28% of individuals were classified as working excessive hours—defined as 52 or more per week.
The results revealed that these individuals showed increased volume in 17 brain areas. Notably, the middle frontal gyrus—a region critical for attention, working memory, and language—grew by approximately 19%. Other affected areas included the superior frontal gyrus, linked to planning and decision-making, and the insula, a deep brain structure involved in autonomic regulation (e.g., breathing, heartbeat, digestion), emotional awareness, and social processing.
Researchers suggested these brain changes could help explain why overworked individuals often experience cognitive fatigue and emotional strain. Dr. Harold Hong, a psychiatrist and medical director at New Waters Recovery who did not participate in the study, commented that although the brain regions increased in size, “bigger is not necessarily better.” He noted that this could indicate the brain is under significant stress and working hard to adapt, and added that the findings underscore the very real neurological toll of chronic overwork.
The health consequences of long working hours extend beyond the brain. A separate study published in the Annals of Occupational and Environmental Medicine tracked more than 14,000 Korean individuals with prediabetes. Researchers found that those who worked over 52 hours per week had a higher chance of developing type 2 diabetes compared to those working 35 to 40 hours weekly. Although the specific biological links are not fully known, lifestyle changes associated with long work hours—such as reduced physical activity, increased smoking or drinking, and elevated stress levels—may play a role. These behaviors are all known risk factors for diabetes, and stress may further interfere with how the body processes glucose.
Cardiovascular risks have also been associated with overwork. A meta-analysis published in Current Cardiology Reports found that working 55 or more hours weekly was linked to a slightly increased risk of coronary heart disease and stroke. This could be due to factors such as heightened blood clotting tendencies and irregular heart rhythms, which compromise cardiovascular function. The WHO has also acknowledged that long hours can significantly increase the likelihood of heart-related illnesses.
Sleep disruption is another major concern. A review published in the International Journal of Environmental Research and Public Health looked at 46 studies spanning two decades and found that short sleep duration—less than six or seven hours per night—was the strongest health risk linked to overwork. Lack of adequate sleep contributes to numerous chronic diseases and undermines mental and physical health.
Wanhyung Lee, a co-author of the brain study, noted in an interview that personal motivation might influence how the brain responds to long hours. People driven by passion, personal fulfillment, or a sense of mission may be more resilient to the negative effects of prolonged stress. In contrast, individuals who work long hours out of obligation or emotional exhaustion may suffer more serious neurological impacts.
Dr. Hong echoed this sentiment, explaining that when people work long hours because they believe in what they’re doing, the resulting stress is often more manageable and may even feel energizing. However, he cautioned that enthusiasm alone isn’t enough to protect one’s health indefinitely. “Even if you love your job, your mind and body still need rest,” he said. “Passion can help you push through, but it doesn’t make you immune to burnout.”
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