We all know just how tiring and stressful working extra hours can be. But a recent study from South Korea offers some concrete and very concerning measurements. Their new study suggests that working long hours may actually reshape the human brain.

In one of the first neuroimaging studies of its kind, researchers at Yonsei University and Chung-Ang University examined brain scans of healthcare workers. They found that those clocking 52 or more hours a week showed noticeable structural differences in key areas of the brain compared with their peers working fewer hours. In particular, the differences were seen in regions involved in executive function (our ability to plan, focus, and regulate behavior) and emotional regulation.

“This study provides preliminary evidence that overwork is associated with structural brain changes, particularly in regions linked to cognition and emotion,” the scientists write.

Your brain on work

The study analyzed 110 healthcare workers, dividing them into two groups. One group worked more than 52 hours per week — the legal upper limit for “standard hours” in South Korea — and the other worked standard hours. The team used two advanced brain imaging techniques (called voxel-based morphometry and atlas-based analysis) to look at gray matter volume across dozens of brain regions.

The first key difference was found in the left caudal middle frontal gyrus. This region makes up about one-third of the frontal lobe of the human brain. The overworked group showed significantly greater brain volume in this region compared to their less-overworked peers.

But this was far from the only difference. Scans showed changes in 17 regions, including the insula, superior frontal gyrus, and superior temporal gyrus. The latter has been involved in the perception of emotions. The insula helps us interpret our internal bodily states and plays a role in emotional awareness, while the middle frontal gyrus is linked to working memory and decision-making.

In short, these are advanced processing regions that basically make us who we are. These parts of the brain affect our ability to think clearly, read a room, and manage stress. And they appear to grow measurably different in those who are consistently overworked.

What does this mean?

The findings are telling, but they don’t establish causation. We don’t know if it’s the overwork that’s causing the changes or something else that’s related. Simply put, there’s a statistically significant relationship between working 52+ hours per week and certain brain volume increases, but based on this study alone, it’s not clear what causes this change.

The researchers point to several plausible culprits: chronic stress, occupational fatigue, and sleep deprivation.

“Our data describe the negative effects of long working hours as a result of altering brain structure,” the team writes.

Sleep problems are another likely contributor. Workers who put in long hours often report poor sleep, and previous studies have linked disrupted sleep to altered brain structure. Overwork, the authors write, is a combination of “physical and emotional overexertion and a lack of rest,” which may cumulatively take a toll on the brain’s architecture.

But, one may ask, isn’t a bigger brain volume a good thing? Doesn’t this mean the brain is benefitting from overwork?

Not necessarily.

While we often associate gray matter increases with brain training or learning, the meaning of such volume changes is more ambiguous in this context. “An increase in the volume, thickness and density of gray matter is commonly interpreted as strengthening of that brain region,” the researchers note. But they also caution, “Research has shown that gray matter is not necessarily positively correlated with brain function.”

Some studies, in fact, suggest that larger volumes in certain regions may reflect maladaptive changes or early signs of dysfunction.

This matters a lot

While we don’t work as much as people did a century ago, we’re still working quite a bit. And the nature of work has recently started to increase work hours.

The modern workplace is increasingly defined by blurred boundaries and extended availability. Remote work, digital communication tools, and global markets make it harder than ever to unplug. For many, overwork is not an exception — it’s the norm.

In the UK, the average person works around one extra hour per day. In the US, almost half of all working people clock over 50 hours a week. Meanwhile, in countries like Korea and Japan, the average work hours are even more intense.

If future research confirms that excessive work reshapes the brain in ways that compromise emotional and cognitive health, it could change how we think about occupational safety — not just as a matter of physical hazards, but of mental architecture.

This was a pilot study, and the researchers are careful not to overstate their findings. The sample size was modest. And participants were all healthcare workers — a group already known for high stress levels and demanding schedules. It’s possible that these individuals were predisposed to the observed brain changes, rather than being shaped by their work schedules.

But, while we need broader studies to confirm these findings, science is increasingly suggesting that excessive work reshapes the brain in ways that compromise emotional and cognitive health

“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,” the researchers conclude.