It has often been dismissed as utopian thinking, a pie-in-the-sky idea that wouldn’t survive contact with reality. But the four-day week has once again quietened critics, as the results of the world’s largest trial suggest that it’s a win-win for employees and their bosses.

The pilot has been described as a ‘breakthrough moment’ in the campaign to send the four-day week mainstream.

Workers who adopted a shorter week with no loss of pay were found to be happier, more productive, took fewer sick days and generated more revenue for their employers, a landmark study has found.

Led by researchers at the University of Cambridge, England, the study assessed the impact of a pioneering four-day week trial, which took place in the U.K. between June and December 2022. Of the 61 firms that took part – among them online retailers, financial service providers and restaurants – 56 pledged to make the move permanent.

Researchers found that 71 per cent of participants reported lower levels of burnout, with 39 per cent saying they were less stressed than before the trial.

What’s more, 60 per cent found that they were better able to combine paid work with care responsibilities, while 62 per cent said it was easier to combine work with their social lives.

Unsurprisingly, this translated into a 65 per cent reduction in sick days, and a 57 per cent drop in the number of staff leaving compared with the same six-month period the previous year.

Concerns that switching workers to a four-day week would impact profits did not materialise. In fact, when compared to a similar period from previous years, organisations reported revenue increases of 35 per cent on average.

“We feel really encouraged by the results, which showed the many ways companies were turning the four-day week from a dream into a realistic policy, with multiple benefits,” said Dr David Frayne, research associate at University of Cambridge. “We think there is a lot here that ought to motivate other companies and industries to give it a try.”

The trial involved two months of preparation, with workshops, coaching, mentoring and peer support for participants. Resisting the idea that the trial must be ‘one-size-fits-all’, each firm designed a policy tailored to its particular needs.

Some academics have questioned the merits of a four-day week, arguing that it can create more stress for employees because they have the same amount of work to do in fewer hours.

Nevertheless, with trials taking place around the world, often with positive results, the shorter working week appears finally to be going mainstream.

Of the U.K. trial, Joe Ryle, director of the 4 Day Week Campaign said : “This is a major breakthrough moment for the movement towards a four-day working week. Across a wide variety of different sectors of the economy, these incredible results show that the four-day week with no loss of pay really works.”