The moment a four-day workweek is mentioned, organizations often feel fear first. If pay stays the same while working hours are reduced, it seems as though performance will be missing in direct proportion to the time that disappears. But work does not always scale with time. Even with the same eight hours, if meetings, approvals, and reporting are packed in, the tangible output becomes thin. On the other hand, when unnecessary procedures are removed, meaningful work can move forward with high density even in less time. That is why the core of a four-day workweek is not a welfare benefit that simply gives people a day off. It is a mechanism that prevents organizations from ignoring how inefficient their work habits have become.

Seen this way, a four-day workweek is not a policy that subtracts one day. It functions as pressure to redesign the remaining weekdays. Organizations with too many meetings are pushed to reduce them, and organizations with too many approval steps are pushed to simplify decisions. In the end, success or failure depends not on the day off, but on how the remaining four days are used.

Debates around the four-day workweek generate many claims, but what creates persuasion is comparable data. A study involving researchers from Boston College and University College Dublin did not treat the four-day workweek as a trend or a satisfaction story. It examined what changes occur when organizations actually intervene. A total of 141 organizations across Australia, Canada, Ireland, New Zealand, the United Kingdom, and the United States participated, and changes were compared before and after implementation for 2,896 workers. The study also included 12 control organizations that did not adopt the four-day workweek, in order to separate natural time trends and expectation-driven effects as much as possible.

One important point is the preparation process. The participating organizations did not jump straight into a four-day schedule. They first went through a phase of reorganizing and cutting work. They reduced unnecessary meetings, simplified processes, and secured focused time, and only then implemented the four-day workweek. In other words, what this study captures is not a simple experiment of taking away a day, but a realistic process in which work is rearranged so that taking away a day can function.

The results were clear in well-being indicators. Burnout decreased, job satisfaction increased, and mental and physical health indicators improved. In the control organizations, changes in the same direction were relatively weaker. Another interesting point was that the magnitude of change differed depending on how much an individual’s working time actually decreased. A pattern was observed in which those whose time decreased more at the individual level tended to show larger improvements.

This change was explained not as a vague feeling, but as a pathway. Improved perceived ability to carry out work, fewer sleep problems, and lower fatigue were presented as key links. Here the argument meets the productivity debate. Fatigue and sleep form the foundation of concentration and judgment. When fatigue accumulates, mistakes increase, rework increases, and communication costs rise. When recovery improves, results can become more stable even within the same amount of time. A four-day workweek can protect performance not simply by making people work less, but by restoring recovery so that the remaining four days become denser and more reliable.

One point, however, should be made clearly. The primary focus of this study is worker well-being, and it is not the same kind of study that measures productivity with identical objective performance metrics across all organizations and then delivers a single definitive number. A more realistic conclusion is this. Whether a four-day workweek undermines performance ultimately remains a question of operations and measurement. Organizations should set up indicators not only for well-being but also for output, quality, errors, rework, and the stability of customer response, and confirm results in their own environment.

The most common failure in real-world adoption is simple: removing a day and leaving everything else unchanged. Then the remaining four days become overloaded, and burnout can be relocated into a different form. That is why the essence of a four-day workweek is not compressing time, but reducing and reorganizing work. Meetings should decrease while decisions become faster. Documentation may increase while unnecessary status reporting should decrease. For organizations where customer response is essential, shift coverage and handovers must become solid first. If handovers are weak, the moment a day is removed a gap appears, and the remaining four days become rougher as people scramble to cover it.

If the adoption sequence is simplified, it can be framed in three steps. First, reduce recurring meetings, redundant approvals, and unnecessary reporting to recover time. Next, create rules that protect focused time so that the recovered time does not leak back into meetings. Finally, reset performance standards more clearly. What counts as performance must become more explicit so that reduced time is not automatically treated as reduced output. It is safer to track not only output but also quality, rework, lead time, and error rates.

In the end, the four-day workweek is not a policy that reduces one day. It is a project that redesigns how work is done. If it is well designed, well-being improves, and that well-being can translate into stable long-term performance through fundamentals like lower fatigue and better sleep. If it is adopted without redesign, the four days may collapse in exchange for a day off. The conclusion always narrows to one point. The key to success is not the day off, but operations.

Fan, Wen; Schor, Juliet B; Kelly, Orla; Gu, Guolin. (2025). Work time reduction via a 4-day workweek finds improvements in workers' well-being. Nature Human Behaviour