Time to let your boss know: A study shows employees function best in a three-day work week.
Japanese researchers analyzed the employment habits and cognitive test scores for 3,000 Australian men and 3,500 women, all over the age of 40. They found working 25 hours per week achieved the best test scores.
“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 cognitive functions,” the study says. “Thus, the degree of intellectual stimulation of work may depend on the required task and working hours, that is, the quality and the quantity of work.”
The researchers theorize that the lower number of work hours are more necessary for people over the age of 40 so they avoid burnout after already spending decades in the workforce.
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The study measured cognitive function with scores on three tests, which included reading words aloud, reciting lists of numbers and linking letters and numbers in a certain pattern under time pressure.
There was little difference in the study’s findings between men and women for peak cognitive function, but there were in other areas.
Women’s cognitive peaks tended to be higher than men’s on all three tests, however, women’s cognitive function dropped off more quickly than men’s after they worked a certain number of hours. For both sexes, not working any hours was associated with a comparably low cognitive level, and men could work between 55 and 60 hours per week before their cognitive function dropped lower than if they were working no hours at all. For women, the number of working hours that produced the same result was between 45 and 50.
“It is found that working hours up to 25–30 hours per week have a positive impact on cognition for males depending on the measure and up to 22–27 hours for females,” the study concludes. “After that, working hours have a negative impact on cognitive functioning.”
The study did not look at younger age groups, so it’s unclear if the results would be the same for all ages or if millennials could work longer hours without mental burnout.