A four-day work week can lead to happier and more productive, dedicated employees, a new global study found.

Workers at companies that instituted a four-day work week – essentially working 80% of their regular hours for the same pay – reported less burnout and better job satisfaction along with improved mental and physical health, researchers report in Nature Human Behavior.

“Across outcomes, the magnitude (of improvement) is larger for the two work-related measures — burnout and job satisfaction — followed by mental health, with the smallest changes reported in physical health,” wrote the research team co-led by Juliet Schor, an economist and sociologist at Boston College.

For the study, researchers conducted six-month trials involving nearly 2,900 employees at 141 businesses or organizations that adopted a four-day work week in Australia, Canada, New Zealand, the U.K., Ireland and the U.S.

The team compared employee well-being at those firms with that of about 290 employees at 12 other companies that didn’t try out the abbreviated work week.

People given a four-day week had, on average, five fewer hours of work per week, results show.

Workers who had a reduction of eight or more hours in their work week reported larger decreases in burnout and increases in job satisfaction and mental health, compared with employees at companies that stuck to a five-day schedule, researchers said.

But even workers who wound up with less time off during their four-day week still received smaller but similar benefits, researchers found.

“There is a clear dose-response relationship for individual-level hours: greater reductions in hours worked predict larger improvements in subjective well-being,” researchers wrote.

Better sleep, improved effectiveness on the job and less fatigue appear to explain the improvements that occurred among employees with a four-day work week, researchers found.

“Increases in perceived work ability — at both company and individual levels — indicate that the work reorganization process opened up by four-day weeks has led to profound changes in the job experience itself, improving workers’ individual and collective sense of performing their jobs well,” researchers wrote.

Overall, the findings suggest that “an organization-wide reduction in hours can stimulate workers to collectively adjust and optimize their workflows, leading to improved work ability and well-being,” researchers concluded.

However, they noted that the companies that participated were already interested in trying a four-day work week, and therefore, might have been more supportive of employee well-being from the start.

More studies including larger numbers of different types of companies are needed to verify that a four-day work week could benefit both employees and their businesses, researchers said.