Commuters cross London Bridge during the morning rush hour on January 31, 2023, in London.
London CNN  — 

One year after the conclusion of the world’s biggest trial of a four-day work week, a large majority of companies that took part were still allowing their employees to work a shorter week and more than half had made the change permanent.

For six months between June and December 2022, workers at 61 organizations in the United Kingdom worked 80% of their usual hours — for the same pay — in exchange for promising to deliver 100% of their usual work.

At least 89% of those firms were still operating the policy and at least 51% had made the four-day week permanent at the end of 2023, according to a report published by one of the organizers of the trial. Two companies did not respond to the researchers compiling the report.

The study was released Wednesday by Autonomy, a think tank that ran the 2022 trial with nonprofit 4 Day Week Global and the 4 Day Week UK Campaign in partnership with researchers from Cambridge and Oxford universities, and Boston College.

The effects of reduced working hours have been overwhelmingly beneficial for staff and their companies, according to the report.

At the end of the trial, employees reported enjoying better physical and mental health, greater work-life balance and general life satisfaction, and less exhaustion from work — and these improvements have been maintained one year on.

“The key point is that the strong findings at six months are not due to novelty or short-term impacts. These effects are real and long-lasting,” said Juliet Schor, professor of sociology at Boston College, which surveyed staff at the companies that participated in the trial.

Managers and CEOs at 28 of the organizations also agreed to answer additional questions. All said the four-day week had a positive impact on their company. Staff turnover fell at half of the organizations, almost a third said the policy had noticeably improved recruitment, and 82% reported beneficial effects on staff well-being.

The Autonomy report also highlights the methods organizations have used to sustain a four-day week, including revising the norms around meetings, work communications and prioritization.

“In this study, it has been clear the four-day week is not just a flash in the pan: companies around the UK have successfully been ‘making it stick’,” the authors wrote.

Close to half of the 61 organizations that took part in the 2022 trial are in marketing and advertising, professional services, and the nonprofit sector. The remainder span a range of industries, including construction, manufacturing, retail, healthcare, and arts and entertainment.

Calls to shorten the working week have multiplied in recent years. These calls have grown louder after millions of employees switched to remote work during the pandemic and stopped commuting, saving time and money.

There have been a number of experiments with the four-day week around the world, including a trial in 2022 across 33 companies, with the majority of workers based in the United States and Ireland.