Four-day work weeks at an unchanged rate of pay makes workers happier, healthier, and more effective, a new study has found.

Using survey data for the 2896 employees involved, authors Wen Fan and Juliet Schor compared work- and health-related indicators (including burnout, job satisfaction, mental and physical health) before and after the intervention.

They also compared these outcomes with those from 285 employees at 12 companies that did not trial the intervention.

Employees with a reduction of eight hours or more per work week self-reported experiencing larger reductions in burnout and improvements in job satisfaction and mental health, as compared with those at companies that maintained a five-day work week.

Similar, though smaller, effects were observed among employees with one- to four-hour and five– to seven-hour reductions in their workweek.

These benefits were partially explained by a reduced number of sleeping problems and levels of fatigue, and improved individual work ability.

The researchers suggested shorter work weeks and reduced working hours without a reduction in salary could help to improve job satisfaction and worker health.

Umbrella Wellbeing principal psychologist Dr Dougal Sutherland, who was not involved in the research, said the study had set a new standard in terms of its scope.

“One important factor contributing to the trial’s success, no doubt, was that participating organisations were coached in the weeks before the trial to find smarter ways of working for staff, streamlining processes, and reducing unnecessary meetings or tasks,” he said.

“Reducing work hours without any supporting workplace scaffolds is unlikely to produce the same results.”

Associate Professor Paula O’Kane of the Otago Business School at the University of Otago said people who were healthier and better rested were more productive.

“While the study centred on a four-day week, the broader implication is clear: flexible and potentially individualised working arrangements can deliver similar benefits,” she said.

“Interestingly, many organisations who participated in the trial were not-for-profits, who often offer flexibility in lieu of higher salaries, perhaps the for-profit sector can learn from them.”