If you're in your 40s and a full-time job, don't take any smart tests at the end of the work week - the results may be disappointing.
A study published in February by researchers at the Melbourne Institute for Applied Socio-Economic Research (Australia) suggests that working more than 25 hours a week could negatively affect the mental performance of people over the age of 40.
Scientists conducted a series of tests on reading, determining patterns and memorization among 6, 000 workers in the appropriate age group in order to determine how the number of hours worked during the week affects a person's cognitive abilities.
Working 25 hours a week (part-time or three days a week) was found to be optimal for cognitive performance, while the study found that mental alertness worsened in both men and women with shorter workweeks.
"Work can stimulate brain activity and help maintain cognitive function in older workers; as the saying goes, what is not used is what is lost, " said project lead researcher Colin Mackenzie, who teaches economics at Keio University in Tokyo, Japan.
"But at the same time, too long hours of work can cause fatigue and physical and / or psychological stress, and thus impair cognitive performance."
But why does this turning point occur precisely at forty?
According to Mackenzie, our "mobile intelligence" - the ability to process information - begins to deteriorate at about age 20, and "crystallized intelligence" - the ability to use the skills, knowledge and experience - after 30 years.
Mackenzie argues that by age 40, most people perform less well on tasks to test memory, pattern detection, and mental alertness.
As the retirement age has been increased in many countries and people are now eligible for a pension later, the latest evidence from Mackenzie's research on cognitive fatigue is significant.
"Work can be a double-edged sword: on the one hand, it can stimulate brain activity, and on the other, too long working hours and certain types of tasks can cause fatigue and stress that can negatively affect cognitive performance, " he said.
So, although in the current economic conditions modern people sometimes have to work much longer than previous generations, it is possible that from an emotional and biological point of view, after 40 years, our brain is no longer ready for stress and performing typical tasks five days a week from nine to six.
Earlier studies have shown that employees of all ages who work overtime can suffer from chronic stress, cognitive impairment, and even mental illness.
In one 1996 experiment by the School of Public Health at Boston University, USA, overtime work has a negative impact on the mental health of auto workers, for example, on assembly lines.
The difference between the results obtained by Mackenzie lies in the fact that the group of scientists led by him was able to establish that similar health and cognitive problems can occur with a much lower workload than was generally believed - in people over the age of 40, working full-time and no overtime.
The negative impact of stress on human mental performance is well understood through research in the field of neuroscience.
Cognitive function is influenced by stress primarily at the hormonal level: primarily through steroids and the stress hormone cortisol, which, in turn, can lead to impairment of short-term memory, concentration, restraint and rational thinking.
However, it is possible that 40 years of age is a turning point for other reasons.
A group of scientists led by Mackenzie is now looking at the factors that influenced the results of their research. For example, the period during which many adults, in addition to full-time work, have at least one person in the care - a child or an elderly relative. This is tantamount to working in two places with little or no rest.
According to the National Union of Caregivers (USA), obtained in last year's survey, in the United States this role is usually performed by a working woman, whose average age is 49 years, and care is usually required by a chronically ill relative (most often a woman, with an average age of dependent - 69 years old).
On average, such care has to be provided for four years, spending 24.4 hours a week on it, in addition to their work and family responsibilities.
Sleep also plays an important role in being able to handle a full work week.
Until recently, people who have achieved a lot in their lives often bragged about how little they sleep.
Former British Prime Minister Margaret Thatcher assured that she was able to work effectively with four hours of sleep a day (although there are footage in the video chronicle of her nodding in broad daylight).
Arianna Huffington, editor-in-chief of the American Internet publication Huffington Post, used to take pride in sleeping five hours a day, but then realized that it was harmful to her health, and now calls lack of sleep "a new type of smoking."
So how much sleep does a person need? The National Sleep Foundation (USA) recommends that people over the age of 26 should sleep more than seven hours a night.
According to Karl Erickson, professor of psychology at the University of Florida (USA), memory and learning ability depend on sleep and rest. The results of Mackenzie's research are consonant with this point of view.
"Restful sleep is a determining factor in performance, " says Erickson.
Erickson's findings also support Mackenzie's suggestion that 40-hour workweeks are not conducive to high performance.
However, Erickson considered this problem not in terms of age categories, but in terms of the optimal number of hours of work per day and week.
“We have found that people who achieve high goals work 21-35 hours a week, but no more than 3-5 hours a day, ” says Erickson.
"Having full freedom of action in relation to work, they devoted no more than the specified number of hours per week, and this indicates that this amount seems to them optimal."
Need to work
Sure, it's nice to talk about how much better it would be to spend less than 40 hours a week in the office, but for many people who depend on income for their survival, this option is financially impossible.
In addition, many of those over 40 would not have thought to reduce the amount of working time, even if they had the opportunity.
They argue that work gives them the incentive they need and consider the research results to be grossly exaggerated.
Among them is Richard Salisbury, a resident of the Blue Mountains, located west of the Australian city of Sydney.
He is now 58 years old and includes a full-time and part-time job as a sole proprietor and full-time employee in an information technology position.
Salisbury disagrees that less is better.
“In fact, I have found that I find it easier to handle the load as I gain experience or just get older, ” he says.
"The idea of a 25-hour work week seems too innovative to me. The vast majority of people with whom I have worked did not experience any changes in cognitive performance, although they spent 35-40 hours in the office."
Penny Evans, 50, a political adviser for a London charity who works four days a week (and used to work there 25 hours a week), cannot unequivocally answer the question of which is better in terms of performance and level. stress - a three-day (25 hours) or four-day work week.
"Three working days a week is great in terms of work-life balance, especially if there are children in the house, but in this case there is a great risk of being out of work and sidelined."
"With four working days a week, I feel a constant connection with my employees, and at the same time I have an extra day off, thanks to which I can cope with the rest of the duties."
Flexibility is key, according to Evans. She believes work-related stress can be dealt with through a widespread belief in the industry that all employees should leave the office no later than 6 p.m.
"However, it is not so easy to indicate the ideal number of working hours per week. When I was young and completely devoted to work with a minimum of other responsibilities, I loved to work until I couldn’t, but I’m not sure that I would want to repeat this feat in modern conditions, when, thanks to electronic mail and social media are happening at an incredibly fast pace. "
Work that does not harm your health
Last year's UK's Most Healthcare Company, sponsored by the University of Cambridge (no civil society organizations participated), ranked sporting goods companies, pharmaceutical companies and information firms at the top of the rankings. technologies.
In all these organizations, employees were given the opportunity to spend time away from the office and maintain their physical health.
For example, some of them offered flexible hours with early endings, while others (such as Sweaty Betty, a sportswear retailer) offered fitness classes at lunchtime.
However, Carol Black, director of Newnam College at the University of Cambridge and chair of the advisory group for the award, is not convinced that older employees should spend less time in the office to achieve good results.
She states: "The most important thing is that the job is good. If it is good, it does not matter how it works - full-time or part-time."