The idea of implementing a four-day workweek is gaining momentum. Over the course of the past years, we’ve seen the governments of New Zealand, Singapore, and Spain openly considering introducing the concept — which not only has wide-ranging benefits for productivity and mental health, but also for the environment.

Now, researchers in Iceland have shared the results of the largest ever trial of a four-day working week, hailing it as an “overwhelming success” that should be tested elsewhere too.

More than one percent of Iceland’s working population participated in the pilot scheme, which cut the usual 40-hour working week to 35-36 hours with no reduction in overall pay, reports The Independent.

The trials — which ran from 2015 to 2019 and involved over 2,500 people — significantly improved productivity and wellbeing, and have already led trade unions in the country to negotiate reduced working hours. Following new agreements struck between 2019 and 2021 after the trials ended, 86 percent of Iceland’s entire workforce now either moved to shorter hours for the same pay or will soon gain the right to.

Participating workers included a mix of nine to five employees and those on non-standard shift patterns. Overall, they reported feeling less stressed and at risk of burnout, and said their health and work-life balance had improved. As a result, productivity and service provision remained the same or improved in the majority of workplaces, according to the researchers behind the study.

“The Icelandic shorter working week journey tells us that not only is it possible to work less in modern times but that progressive change is possible too,” said Gudmundur D. Haraldsson, a researcher at Alda, one of the think tanks that carried out the analysis.