The optimum working week for people aged over 40 lasts between 25 and 30 hours, according to research from the University of Melbourne.
Researchers found that working part-time aided the cognitive function of Australians of that age, but that working beyond three days a week triggered a level of stress and fatigue which undid the benefits.
More than 3,000 men and 3,500 women over the age of 40 in Australia were studied in the analysis of work habits. They were tested in three areas: memory, reading and perception.
“In all three cases [tests] it was found around 25-30 hours of work per week will maximise your cognitive skill,” Professor Colin McKenzie at Keio University who took part in the study told ABC.
“And going for less hours or more hours reduces your cognitive skills.”
Working as much as 50-60 hours a week was just as bad as not working at all, according to McKenzie.
He said: “Too much work leads to stress and fatigue and that’s probably the key cause of this decline in cognitive skills after 25-30 hours a week.”
The researchers did not identify differences between men and women in terms of the length of time they worked for each week.
McKenzie’s study comes as many countries raise their retirement age. The British state pension age is set to skyrocket over coming years as life expectancy rises and Treasury budgets are stretched.
The state pension age is currently 65 for men and 60 for women, but it is set to rise to 66 by 2020 and 67 by as soon as 2026.
McKenzie said the results would vary in different countries.
“If the number of hours doesn’t peak at the same place, there may be systemic reasons for that difference, for example Australia has four weeks of annual leave which tends to be longer than Japan,” Professor McKenzie said.
“So these chances to refresh your body and brain may be important in determining the optimum peak.”
He told ABC he was interested in looking at the impact of work on other areas of health too.