The four-day workweek was tested worldwide, and the results are surprising

Introduction: what if working less actually meant producing more

An idea that seemed unrealistic twenty years ago

For decades, the five-day workweek seemed as fixed as the sunrise. Almost no one questioned this rhythm inherited from the industrial revolution. And yet, in recent years, a growing number of countries have decided to test an almost heretical hypothesis: shrinking the week to four days, without touching pay, might cost nothing in terms of productivity — and could even improve it. Did you know this experiment is no longer just a fantasy dreamed up by trendy startups, but a serious subject of study for international organizations such as the International Labour Organization or the OECD.

What makes this story fascinating is its scale. We are not talking about a handful of isolated companies quietly running a side experiment. Entire governments, public administrations and thousands of employees have taken part in full-scale trials, complete with rigorous methodologies, control groups and scientific monitoring. The United Kingdom, Iceland and Japan are among the most thoroughly documented testing grounds, each with its own cultural and economic particularities.

Why this question fascinates researchers so much

Workplace productivity has been an obsession for economists ever since the industrial revolution. For a long time it was assumed there was a direct, linear relationship between hours worked and output produced. Yet several studies in labor science suggest that this relationship breaks down past a certain threshold: fatigue, stress and disengagement eventually erode individual efficiency. It is precisely this hypothesis that the four-day-week experiments set out to test empirically.

The fact that institutions as cautious as ministries or government agencies agreed to fund and oversee these trials speaks to a profound shift in mindset. The goal is no longer simply to make people work longer, but to understand how to structure working time to maximize both employee well-being and the economic results of organizations.

The Icelandic experiment: the lab that changed everything

A national trial run over several years

It is almost certainly Iceland that offers the most spectacular example of this transformation. Between 2015 and 2019, the country ran two major pilot trials involving more than 2,500 workers, roughly 1% of Iceland's total working population. That figure may seem modest on a global scale, but relative to the size of Iceland, it is a considerable sample, spanning sectors as varied as hospitals, daycare centers, administrative offices and social services.

Participants moved from a forty-hour week to a week of thirty-five to thirty-six hours, with no reduction in pay. The stated goal wasn't purely economic: it was also about improving the work-life balance in a country with a particularly high female employment rate, where the issue of mental domestic load was especially pressing.

Results so conclusive they changed the rules

The researchers tasked with evaluating these trials concluded that productivity and public services delivered remained stable, and even improved in several cases. Employee well-being saw a clear boost, with a measurable drop in stress and burnout symptoms. The result surprised even the experiment's own organizers, who were used to well-being gains coming at the cost of lost output.

The impact of this Icelandic experiment was so significant that it led to a permanent renegotiation of working hours for a majority of the country's workforce, far beyond the original sample tested. Today, a significant share of Icelandic workers enjoy reduced working hours or greater flexibility, a direct legacy of trials run nearly a decade ago. It's a rare example of a field-based social experiment that directly reshaped national labor norms.

What makes the Icelandic case even more remarkable is how quickly the results moved from a research footnote to a matter of national policy. Trade unions and employer associations, groups that rarely agree on much, both pointed to the same dataset when negotiating new collective agreements. That convergence, rare in labor relations, gave the reform a legitimacy that purely academic studies almost never achieve on their own.

The United Kingdom: the largest trial ever run in the private sector

Dozens of companies volunteered for the experiment

The United Kingdom followed a different path, relying on voluntary participation from private companies rather than a state-led rollout. Dozens of organizations, ranging from small communications agencies to financial firms, agreed to cut employees' working time to four days a week while keeping full pay, as part of a coordinated trial backed by research bodies and government representatives.

This approach offered an interesting methodological advantage: it allowed comparisons across companies with very different profiles, in sectors ranging from marketing to construction to financial services. Such a broad sectoral spread gives the results a scope well beyond the isolated case of a tech-savvy company trying to attract young talent.

Productivity held steady or even improved

Monitoring bodies found that the vast majority of participating companies chose to continue the experiment beyond the initial trial period — a strong signal of satisfaction. Internal performance indicators, whether revenue or perceived quality of work, remained broadly stable, with notable improvement in some companies.

On the employee side, reported benefits included reduced stress levels, lower absenteeism and better work-life balance. These results, documented by institutions such as the British government and covered by the international business press, helped fuel a wider public debate on reforming working time across Western economies.

Japan: a radically different cultural context

Breaking with a culture of overwork

The Japanese case deserves particular attention because it unfolds in a cultural context very different from Northern Europe's. Japan is historically associated with an intense work culture, symbolized by the term karoshi, meaning death from overwork. In that context, even the idea of experimenting with a four-day week represents a particularly significant paradigm shift.

Some major Japanese companies, encouraged by a government worried about falling birth rates and widespread burnout, have tested shortened-week arrangements. The goal went beyond productivity alone: it was also about responding to a demographic crisis and a labor shortage by giving employees more time for their personal and family lives.

Promising results despite cultural resistance

Early feedback from these Japanese experiments suggests benefits similar to those seen in Europe: output maintained, improved team morale and reduced overwork. However, adoption remains slower and more cautious than elsewhere, due to a strong cultural attachment to physical presence at the office and the idea that hours spent at work reflect an employee's commitment.

This cultural resistance illustrates an essential point stressed by several researchers in economics and social sciences: the success of reduced working time doesn't depend solely on measurable economic factors, but also on organizational environment and social norms specific to each country. What works in Iceland doesn't automatically transfer to Japan without adaptation.

Some Japanese firms have tried a middle path, offering the fifth day off as an optional benefit rather than a blanket policy, letting individual teams decide whether the switch suits their workload. This flexible rollout, while slower than a nationwide mandate, may ultimately prove more durable, since it avoids forcing a single model onto industries with wildly different staffing needs and client expectations.

How to explain this apparent paradox of stable productivity

Reorganizing work rather than simply compressing it

One of the most interesting lessons from these experiments concerns method. Companies that successfully made the transition didn't just remove a workday while keeping the same habits over four days. They used the opportunity to fundamentally rethink their organization: fewer meetings, limiting interruptions, prioritizing high-value tasks. Perhaps this is where the real secret of this success lies: not working less, but working differently.

Data reported in the international business press shows that time saved by cutting activities deemed unproductive, such as redundant meetings or excessive email management, largely offsets the loss of hours present at work. This deep reorganization of work explains in part why measured productivity stays stable despite an apparent reduction in available time.

The human factor: stronger motivation and engagement

Beyond organizational aspects, a human factor appears to play a decisive role. Employees who get an extra day off report higher levels of motivation and engagement when they are at work. This sense of recognition, combined with better fatigue management, seems to offset the reduction in time present with greater intensity during the hours actually worked.

This dynamic isn't unique to one country: it has been observed in both the Icelandic and British trials, suggesting a relatively universal psychological mechanism. One could almost say these experiments are redefining what it truly means to be productive at work. It is no longer just about counting hours, but about measuring what is actually accomplished during that time.

The limits and questions that remain unresolved

Not every sector faces this transition equally

It would nonetheless be misleading to present the four-day week as a universal solution applicable without nuance to every profession. Sectors that depend on continuous presence, such as hospitals, factories running around the clock or certain emergency services, face far more complex logistical challenges than office jobs. Reorganizing schedules in these sectors often requires additional hiring, which can represent a significant cost for the organizations concerned.

Experts consulted by international organizations also stress that the positive results recorded so far mostly come from voluntary trials, run by companies and administrations already motivated by the project. This selection of participants could introduce an optimistic bias into overall results, a point researchers continue to study closely.

There is also the question of long-term durability. A handful of companies that adopted the four-day week in the early trials have since quietly reverted to five days, citing client demands or staffing shortages that made the shorter schedule unsustainable. Researchers tracking these reversals argue they deserve just as much attention as the success stories, since understanding why some organizations retreat is essential to designing policies that actually hold up over time.

Toward a gradual worldwide rollout

Despite these methodological reservations, the momentum seems irreversible. More and more countries, companies and public administrations are closely watching the Icelandic, British and Japanese results to assess the case for wider adoption. Similar discussions have emerged in other developed economies, fueled by data published by organizations such as the OECD, which closely tracks changes in working time internationally.

This movement fits into a broader reflection on the future of work, accelerated by technological change and the shifting expectations of newer generations regarding work-life balance. What seemed like social science fiction a generation ago is now documented, quantified and debated at the highest institutional level.

Whatever happens next, the sheer volume of evidence now available means future debates on working time will have to engage with real data rather than mere intuition. That alone marks a quiet revolution in how societies think about the relationship between hours worked and value created.

By Maxime Marquette, columnist

Sources

Primary sources

International Labour Organization — Resources on working time and productivity — Accessed 2026

British Government — Data and monitoring of the national four-day-week trial — Accessed 2026

OECD — Statistics and analyses on working time across member countries — Accessed 2026

Secondary sources

BBC News Business — Reporting on four-day-week experiments — Accessed 2026

The Guardian Business — Analysis on reduced working time in the UK — Accessed 2026

Smithsonian Magazine, Innovation section — Historical insight into the evolution of working time — Accessed 2026