Should 40-somethings Only Work 20-something Hours?

A study showed that cognitive functioning declined for workers over 40 after they did more than 25 hours. Thomas Barwick/Getty Images A study showed that cognitive functioning declined for workers over 40 after they did more than 25 hours. Thomas Barwick/Getty Images
A study showed that cognitive functioning declined for workers over 40 after they did more than 25 hours. Thomas Barwick/Getty Images

An Australian study made headlines recently by claiming that a three-day work week is the best way to maintain a sharp brain as you age. The researchers analyzed cognitive test data from a large sample of older Australian workers (40 and above) and found that brain performance was lower in individuals who worked more than 25 hours a week. The culprit, the researchers believe, is stress.

"Work can stimulate brain activity and help maintain cognitive functions for elderly workers, but at the same time, excessively long working hours can cause fatigue and physical and/or psychological stress, which potentially damage cognitive functioning," says researcher Colin McKenzie, professor of economics at Keio University, Japan, via email. Cognitive functions are brain functions like reasoning, memory and attention.

Does this mean that anyone over 40 should immediately submit an HR request for Tuesdays and Thursdays off? Not quite. While a 25-hour work week is attractive for many reasons, it likely wouldn't pay nearly enough to cover the bills, even if workplaces were flexible enough to offer it (they aren't). So what's an aging worker to do?

The choice, it turns out, may not be that stark. A closer look at the Australian study reveals plenty of good reasons for older workers to stay on the job as long as they want. "We cannot and do not claim that we should be choosing to work in part-time jobs instead of full-time positions. To answer this question, we need further research on working patterns," says McKenzie. "This is because the degree of intellectual stimulation of work for brain activity would depend on both the 'quantity' and the 'quality' of work."

Different Kinds of Intelligence

Jacquelyn James, co-director of the Center on Aging & Work at Boston College, would agree. She studies the aging of America's workforce and the changing nature of retirement. 

"We know that different types of jobs carry different types of stress, and the researchers don't control for any aspect of job quality," says James, "It makes a big difference whether the stress is a 'positive' stress, like a challenge that's fun to meet, or a miserable day-to-day existence."

She also has a problem with the way that the researchers defined cognitive ability, based mostly on "fluid intelligence" tests that gauged brain speed, such as memorizing a string of numbers and reciting them backwards, or correctly reading wrongly spelled words. James says that decades of studies have long proven that we lose some cognitive quickness as we age, but that's only one type of intelligence.

"Older adults do better than younger adults in what's called crystallized intelligence," says James. "Crystallized intelligence depends on your experience of the world, your education in broader sense, the informal learning experiences of every day — the kinds of things that you gather over time."

This type of experience-based intelligence can be hugely important in the workplace, says David DeLong, president of Smart Workforce Strategies and author of "Lost Knowledge: Confronting the Threat of an Aging Workforce." 

"In manufacturing, for example, older workers are able to diagnose problems faster and set about solving them quicker," says DeLong. "They can recognize a faulty machine before a less-experienced worker. The experiential knowledge of older workers will often trump any cognitive deficit that might come with age."

Age Discrimination Ammunition?

"I would hate to see this kind of research being used to argue that older workers need to work fewer hours," add James. "That only feeds the age discrimination that's already well-entrenched in our society."

Counters McKenzie, "Our research is not about whether the productivity of older workers is lower than that of younger workers. We are examining whether engagement with work can prevent declining of cognitive functioning ... Our results show that, on average, people aged 40 and over can maximize the benefits of work on their cognitive functioning by working around 25 hours a week. That is, no work is worse than full-time work in terms of maintaining cognitive functioning, but full-time work is not maximizing the positive effects of work."

Even if a long work week has potential side effects, there are still plenty of good reasons why a growing number of Americans are choosing to continue working full-time into their late 60s and 70s. Financial concerns are the biggest reason why older workers are delaying retirement. As we live longer, we need to stretch our working years to save more. But money isn't the only motivator.

"People want to continue to work, because work is what they've spent their lives building their capacities to do," says James of the Center on Aging & Work. "Studies show that older workers are more engaged in their work than younger workers are. Once we get to a certain age, we've found our way to something that we like doing and we just want to keep doing it."

James has a caveat, though. She thinks it's dangerous to perpetuate the idea that all of us can keep working until we drop.

"People can think they will work until their 70s, but they might not be able to for lots of reasons," says James. "Health is the number one reason people drop out of work. Next is taking care of family members or losing a job to layoffs."