Employment. Four-day week: health, productivity... working less is beneficial, according to a study

Work less to feel better? A study published Monday in the scientific journal Nature suggests that a four-day week —without a pay cut—would be beneficial for workers' mental and physical health.

Conducted on a record sample size for the subject, in 141 companies from six English-speaking countries over a six-month period, this research found that employees who switched from a five-day to a four-day week were less stressed than before, saw their sleep improve, and their fatigue decrease. The number of cases of burnout also decreased.

Depending on the company, the employees monitored worked between five and eight hours less per day than before. The workers whose working hours were reduced the most were also those who showed the greatest decrease in burnout.

Elimination of “unnecessary” activities and increase in productivity

Business productivity—and employees' sense of effectiveness—didn't decrease when they went from five to four workdays. "When workers want to produce the same amount of work in less time, you'd think their stress levels would increase. But we saw the opposite," explains the study's lead author, Wen Fan, a sociologist at Boston University. The reason: this experiment allowed companies to restructure and employees to optimize their time. So, no more "useless" activities, like meetings.

The experiment clearly convinced employers, as 90% of companies decided to maintain the four-day week. It should be noted that not all of the benefits of the four-day week highlighted by the study were observed in the 12 “control” companies, which served as a comparison for the researchers.

Some limitations

Several other studies conducted in other countries in recent years, notably in the United Kingdom and Germany, have reached similar conclusions. The study published in Nature , however, is the largest ever conducted.

Of course, the four-day week isn't applicable in all sectors. And the study only included volunteer companies, small or medium-sized, in relatively affluent environments. Further studies are needed to observe the impact of the four-day week in other sectors, the authors acknowledge, while still emphasizing the solution this format represents for combating burnout.

The French overwhelmingly in favor

In France, 70% of people - including 77% of working people - say they are in favor of the four-day week, according to a survey conducted by Ifop for Politis in the spring of 2024. However, very few companies offer this format to their employees - between 70 and 150, according to a parliamentary report presented to the National Assembly last October, and rather in favor of a reduction in the number of days worked per week.

The same report believes that the five-day workweek "is neither a universal cure for workplace ills nor a false good idea" in France. It explained that in some cases, this arrangement improved employees' productivity and psychological health and contributed to a better work-life balance. However, the report—like some unions—warned about the risk of longer workdays that could generate additional fatigue and stress. This is also the position of several employer organizations.

An experiment, led by the organization 4dayweek , began in spring 2025 with French SMEs interested in trying out the four-day week for several months. The results will not be known until the end of the test. But at a time when the Prime Minister is talking about eliminating public holidays, reducing the number of working days per week does not seem to be on the agenda...