(CNN) — Men participating in the world's biggest trial of a four-day work week spent much more time with their children, organizers say.

For six months starting in June last year, about 2,900 workers across 61 companies 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. That is the biggest number of companies to ever take part in such a trial, according to organizers 4 Day Week Global (4DWG), a nonprofit organization.

Some 1,238 workers completed a final survey about their experience. The results were published on Tuesday.

The time male workers spent looking after their children rose by 27 percent, according to time diaries they kept during the trial. By comparison, female participants reported an increase of 13 percent in childcare.

"It is wonderful to see that we can shift the dial and start to create more balance of care duties in households," Charlotte Lockhart, founder and managing director of 4DWG, told CNN.

Among all workers, 60 percent said they were better able to combine their jobs with caring responsibilities, while 62 percent said it was easier to have a social life.

While both men and women benefited from the new schedule, "women's experience is generally better," Dr Dale Whelehan, chief executive of 4DWG, said in a press release.

"This is the case for [reduced] burnout, life and job satisfaction, mental health and reduced commuting time," he said.

4DWG ran the study with Autonomy, a think tank, the 4 Day Week UK Campaign, as well as in partnership with researchers from Cambridge University, Oxford University and Boston College.

It was "a resounding success," according to organizers, with 92 percent of the 61 participating organizations continuing with the four-day week beyond the end of the trial. About 71 percent of workers said they had "lower levels of burnout" by the end of the six months, while 40 percent experienced fewer sleep difficulties.

Life changing

Last year, managers and employees in the trial described to CNN how the extra day off had changed their lives for the better, giving them more time to run errands, take up hobbies, and simply recharge.

The UK study follows a separate international trial last year involving 903 workers across 33 companies, with the majority of workers based in the United States and Ireland.

That experiment was even more successful: none of the 27 companies that responded to 4DWG's survey said they were leaning towards or planning on returning to their former five-day routine.

Calls to shorten the working week have gathered steam 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.

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