Here is the maximum number of hours you should work each week, according to science

According to a study conducted by Australian researchers, working full-time after a certain age could have very harmful consequences on our cognitive abilities.

Work is healthy but to what extent? At a time when our professional lives are taking up more and more of our free time, more and more of us are also questioning the relevance of full-time jobs that keep us busy for 40, 50 or even 60 hours a week.

But according to an Australian study published in 2016 by researchers at the Melbourne Institute of Applied Economic and Social Research, it seems that if you're over 40, working more than 25 hours a week could simply harm your brain, and thus affect your intellect.

Is full-time work bad for our brains?

To arrive at this slightly worrying conclusion in view of the way our societies function, the team carried out reading, schematisation and memory tests on more than 6,000 workers over the age of 40, to see how the number of hours they work each week could affect their cognitive abilities.

Why 40? As Colin McKenzie, professor of economics at Keio University in Tokyo and lead author of the research explains, our ‘fluid intelligence’—the way we process information—begins to decline around the age of 20, and ‘crystallised intelligence’—or the ability to use skills, knowledge and experience—starts to decline after 30. And by the age of 40, most people perform worse on memory tests, pattern recognition and mental agility exercises.

At the end of the experiment, the researchers concluded that excessive working hours can, unsurprisingly, lead to fatigue and physical and/or psychological stress, which can damage cognitive functioning.

working 25 hours a week (part-time or three days a week) is the optimal amount for over 40s Annie Spratt / Unsplash

How much time should we work each week?

In the study, McKenzie and his other researchers state that working 25 hours a week (part-time or three days a week) is the optimal amount of time spent on our jobs each week so as not to impact cognitive functioning. Conversely, working less than 25 hours a week would be detrimental to brain agility for both men and women.

McKenzie said, as reported by the BBC:

Work can stimulate brain activity and can help maintain cognitive functions for elderly workers, the ‘lose it or use it’ hypothesis.


But at the same time, excessively long working hours can cause fatigue and physical and/or psychological stress, which potentially damage cognitive functioning.
Work can be a double-edged sword, in that it can stimulate brain activity, but at the same time, long working hours and certain types of tasks can cause fatigue and stress which potentially damage cognition.

In short, it's all about balance in order to preserve your mental health and not end up burning out. But from the age of 40 onwards, lifting your feet a little, if you can, seems the best thing to do.

This article was translated from Gentside FR.

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