A new study has revealed that, after 25 hours worked per week, performance decreases and a multitude of capacities are reduced, from memory to the processing of certain information. Working 40 hours a week, or 8 hours a day, with overtime often added, is not suitable for the worker or for productivity at the company level. Probably, any employee has noticed that after a certain threshold this performance would decrease significantly, but this feeling turns out to be accompanied – and defended – by a long history of scientific studies. A search by the Melbourne Institute of Applied Economic and Social Research Australia revealed that the optimal number of work hours is 25 per week, which is equivalent to 3 days instead of 5, especially if you are over 40 years old. One step further, the research says, cognitive abilities decline dramatically and fatigue and stress ensue. The idea is a complete counterpoint to the philosophy of Elon Musk, who boasts of working up to 80 hours a week. In this way, the effects are felt in the loss of memory, language skills, concentration and the speed of information processing, as well as maintaining certain cognitive functions that only remain at high levels during this period. After him, fatigue drastically lessens them. The 7 best refrigerators of 2019 that you can buy right now, with a buying guide, comparison and tips to choose the best one for your kitchen. But if reducing hours can seem like a utopia, the truth is that it is already a reality in the Netherlands, for example, where since 2000 a law has been in force that allows workers to reduce hours and request work from part time. The 4-day week is common and adopted, among others, by 86% of women with children and 12% of parents. Read more: The Prime Minister of Finland wants to reduce the working day to 6 hours On the other hand, according to a study by vouchercloud, productivity in a working day is limited to a few hours. The research, based on a series of questions to hundreds of British workers, revealed what they consider to be the “real pace” of employees and the hours at which they achieved maximum performance (and when it began to decline). The majority, 79%, confessed not being productive all day; at most, on average, 2 hours and 53 minutes, the limit of performance. A second group, on the other hand, was elicited that in 65% of cases they could not work without distractions. The main reason: social networks, reading the news or arguing with other colleagues, but also eating or smoking. Many of them also spent huge amounts of time looking for another job. In this case, the Spanish are not like to complain either. According to an OECD study, Spaniards spend 1,691 hours a year at work, less than the organization’s average (1,766 hours). The most disadvantaged (above, of course) are Mexicans, followed by South Korea and Greece. At the opposite extreme are Germany, the Netherlands and Norway. John Maynard Keynes has already predicted that thanks to technology we could work less: By 2030, he argued, 15 hours per week would become the norm. We’re still a long way off, unless you intended to subtract the hours we spend on the internet. This article was published in Business Insider Spain by Luis Casal.