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Working more than 40 hours a week isn’t just tiring; it is actively harming your brain and body.

Newsweek spoke to experts in psychiatry and workplace wellness about the risk of health issues and impaired cognitive function that arise from overworking. While research highlights the profound consequences of chronic overwork, calls for a re-evaluation of pervasive “hustle culture” are growing.

For years, the relentless pursuit of productivity has pushed many beyond the traditional 40-hour working week. However, Dr. Ashwini Nadkarni, MD, an assistant professor of psychiatry at Harvard Medical School, pointed to noteworthy neurological impacts.

Stock image: A woman works late at her home desk with a lamp on. Stock image: A woman works late at her home desk with a lamp on. cyano66/Getty Images

“While research shows that long working hours can increase the risk of metabolic disorders, such as diabetes, observational studies … have shown that such work patterns are associated with changes in the brain responsible for executive functioning,” Nadkarni said. She added that this includes our ability to “sequence, organize, abstract, and plan.”

Nadkarni noted that one analysis for those working 52 or more hours a week showed a 19 percent increase in the volume of the middle frontal gyrus, an area of the brain associated with attention and working memory.

“Additional research has also shown a relationship between excessive working hours and reduced processing speed,” Nadkarni said. For her, the takeaway is clear: “Rest therefore serves an important function in memory consolidation and learning.”

Adding her voice to the long-hours warning is Christina Muller, a licensed workplace mental health expert and strategist at R3 Continuum, who consults with Fortune 500 companies and health-care systems.

Often supporting employees navigating chronic overwork, Muller told Newsweek that sleep disruption is “often the first and most-overlooked consequence” of this.

“Without sufficient time to rest, our brains don’t get the opportunity to reset and integrate the day’s information,” Muller said. “This sleep debt affects the brain’s ability to consolidate memory, regulate emotions and access creative or strategic thinking. Our brains need rest to process and embed the information we take in each day.

“When we’re overworked, we are in survival mode,” Muller added. “Research consistently shows that chronic overwork impairs executive functioning, working memory and processing speed, and these effects compound over time.”

Symptoms Might Not Be Noticeable

The insidious nature of chronic overwork means many people don’t realize the damage until it is severe.

Muller likened it to a hidden accumulation: “[People] are often so focused on spinning in the proverbial hamster wheel that, until they fall ill or have relationship issues, the effects can feel subtle or even manageable,” she said. “It’s like compounding interest against yourself that builds over time.”

Nadkarni highlighted a major misconception fueled by hustle culture—that taking time for restoration is counterproductive. In fact, she said, resting is crucial for good cognitive functioning.

Muller echoed this, saying that one of the greatest myths of hustle culture is that “pushing harder equals producing more. In truth, sustainable performance requires recovery,” she said.

High-quality sleep, adequate boundaries and intentional downtime are “biological necessities” for long-term cognitive health and professional performance, Muller added. Otherwise, workers are at risk of long-term burnout, mental or physical illness.

The 4-Day Working Week: A Possible Solution

The conversation around reducing working hours to improve well-being is gaining traction, with the four-day working week emerging as a leading answer.

A recent study led by Professor Brendan Burchell and Dr. David Frayne from the University of Cambridge investigated the practical and equitable impact of a four-day working week.

The research involved a major trial in the U.K. and was the largest trial of its kind, involving 61 companies and approximately 2,900 employees across various sectors—and the results were compelling.

“Before the trial, many questioned whether we would see an increase in productivity to offset the reduction in working time—but this is exactly what we found,” Burchell said in a news release.

The study also found that anxiety and fatigue decreased across the sample, while mental and physical health “improved.”

The evidence between experts and written research seems clear: prioritizing rest and sustainable working hours is not a luxury, but a necessity for our own health—and, in turn, we might even become even more productive workers after all.