Workers who took part in the trial were paid their regular salary and produced the same amount as they usually would but only worked 80% of their normal hours.

The overall rating given to the four-day week by the companies who took part was 8.3 out of 10. Business performance and productivity were scored at 7.5 out of 10 while revenue rose 1.4% on average.

The number of staff leaving fell by 57% over the trial period.

Most employees want a four-day week

Of the employees that took part, 90% said they would like to continue the four-day week and 55% said they saw an increase in their abilities at work while 15% said no amount of money would persuade them to return to a five-day work week.

Benefits of the trial included lower stress levels (39%) and 43% of workers said their mental health improved.

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Levels of burnout were down 71%; 54% of workers said they saw a fall in negative emotions; 37% saw improvements in physical health; 46% saw a fall in fatigue; and 40% saw a fall in difficulties with sleep.

Another benefit of the shorter working week was having more time to help with caring responsibilities.

The time men spent looking after children rose to 27%, compared to 12% for women. While 73% said they had greater satisfaction with their time and 60% found an increased ability to combine paid work with caring responsibilities.

Sainsbury’s testing new ways to be more efficient and flexible

Meanwhile, Sainsbury’s has told YourMoney.com that it is ‘testing new ways’ to evolve its working practices.

Sainsbury’s said it was not trialling a four-day week or condensed working hours but it was “currently testing new ways to be more efficient and offer improved flexibility.”

A Sainsbury’s spokesperson said: “We are always looking to evolve our ways of working to ensure we can do the best possible job for customers while continuing to be a brilliant place to work for our colleagues. We are currently testing new ways to be more efficient and offer improved flexibility.

“At the same time, we are committed to supporting colleagues when they need it most. That’s why we have recently invested £185 million to give retail hourly-paid colleagues a pay rise to help them manage increasing bills. This is the second pay rise we have given retail colleagues this financial year, taking Sainsbury’s total investment in colleague pay to £205 million.”