A four-day working week could bring significant benefits to your mental and physical health, all while improving your performance. At least that’s according to a new study by researchers in the US and Ireland.

The best bit? The study, published in journal Nature Human Behaviour, didn’t reduce income as part of the trial. That’s because, as you might imagine, reduced pay can contribute to stress. The workers were able to maintain their normal output due to the improved working environment, alongside reduced sleeping problems and lower levels of fatigue.

“We see global trends (not just in high-income countries, but in many low- and middle-income countries) where workers are struggling with burnout, long work hours and little time for themselves and for their families,” study author Wen Fan, associate professor of sociology at Boston College in the US, told BBC Science Focus.

“Our four-day work week is a potential way to reimagine how we can reconstruct the work arrangement in order for workers to benefit, and the societies to benefit as well.”

The sociologists behind the study, from Boston College and University College Dublin, conducted six-month trials involving almost 3,000 employees across 141 organisations based in Australia, Canada, Ireland, New Zealand, the UK and the US. Employees were given a reduction in their weekly working time of one to four hours, five to seven hours, or eight hours.

Before and after the six months, employee wellbeing was evaluated in four categories: burnout, job satisfaction, overall psychological wellbeing and physical health (which is a key health predictor of mortality).

Meanwhile, the researchers compared their survey results with those from 285 employees at 12 companies that didn’t trial a reduced working week.

Employees in all three groups who had their hours reduced saw significant benefits to their health, as well as improvements in burnout and job satisfaction categories. The people whose work hours reduced by eight hours saw the largest benefits. What’s more, 90 per cent of the companies that signed up for the trial continued the four-day work week after the trial had ended.

Trials are already underway across the world to test the impacts of reduced hours on both employees’ health and organisational output. Reduced hours can also take the form of a six-hour working day or a 20-per-cent reduction in working time. One of the largest is the 4 Day Week Global (4DWG) initiative, which has received participation from 375 companies around the world.

Key limitations of the study were that companies had to volunteer to participate, meaning many were small companies, and they were all in English speaking countries. In the future,  the researchers hope that government-sponsored trials will allow for more randomised studies.

Meanwhile, the researchers behind the new study are investigating the environmental impact of the four-day work week, as some of the employees also volunteered to have their carbon footprint tracked.

Wen thinks there could be benefits to the environment – such as less pollution from commuting – as well as those to workers and employers. She said: “Comparing across countries at the macro level, countries with shorter work weeks or work hours tend to have better environmental outcomes.”

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Wen Fan is an associate professor in the department of sociology at Boston College, in the US. As well as Nature Human Behaviour, her research has been published in the journals Social Forces, Work and Occupations, and Advances in Life Course Research.