The world's biggest trial of a four-day working week published its findings on Tuesday to claim its success as an overwhelming majority of participating companies declared they would continue with the new working model.

In the UK, a total of 61 companies across different sectors were involved in the six-month pilot scheme between June and December last year.

Conducted by non-profit 4 Day Week Global, the UK's 4 Day Week Campaign and think-tank Autonomy, nearly 3,000 workers were guided through a shorter working week at the same pay as their usual five-day working week.

"Results are largely steady across workplaces of varying sizes, demonstrating this is an innovation which works for many types of organisations," said Lead Researcher Professor Juliet Schor, from Boston College - one the institutions involved in the trial along with Oxford and Cambridge universities.

"There are also some interesting differences. We found that employees in non-profits and professional services had a larger average increase in time spent exercising, while those in construction/manufacturing enjoyed the largest reductions in burnout and sleep problems," said Schor.

The overall results show that almost every organisation plans to stick to a four-day week post-trial, with 91 per cent definitely continuing or planning to continue, and a further 4 per cent leaning towards continuing. Only 4 per cent of participants have said they are not continuing with a shorter week.

Companies rated their experience of the trials an average of 8.5 out of 10, with business productivity and business performance each scoring 7.5 on 10. Revenue rose by 35 per cent over the trial periods when compared to similar periods from the previous year, and hiring increased while absenteeism decreased, the findings reveal.

Meanwhile, the health and wellbeing of employees also improved, with significant increases observed in physical and mental health, time spent exercising, and overall life and job satisfaction. Rates of stress, burnout and fatigue all fell, while problems with sleep declined. According to the researchers, environmental outcomes were also encouraging, with commuting time falling across the full sample by a half hour per week.

"While both men and women benefit from a 4-day week, women's experience is generally better. This is the case for burnout, life and job satisfaction, mental health and reduced commuting time. Encouragingly, the burden of non-work duties appears to be balancing out, with more men taking on a greater share of housework and childcare," said Dr Dale Whelehen, CEO of 4 Day Week Global.

Going forward, the plan is for the team to expand the pilot schemes to other parts of the world.

"Our team is delighted to be expanding the arguments in favour of a 4 day week today with this new world-class academic research, and we look forward to adding our Australasian pilot results to this data set in the coming weeks and our European, South African, Brazilian and North American results in the coming months," said Charlotte Lockhart, Co-founder and Managing Director of 4 Day Week Global.

The employers and workers in the pilot were given access to the expertise, tools and resources such as workshops and mentoring that the researchers felt would be needed to run a smooth and successful trial.