The University of Sussex and Thrive, a learning technology company, have released the results of the UK’s first medical trial of a four-day work week.

The three-month study, held between July and October 2024, examined the impact of a reduced working week on employee wellbeing and productivity.

Data collected from Thrive employees included MRI scans, blood tests, and sleep tracking, alongside weekly questionnaires on workplace experience and wellbeing. Customer feedback was also assessed to gauge any changes in service quality, while sales and product metrics measured business productivity.

Wellbeing Benefits of a Shorter Week

The trial revealed marked improvements in the physical and mental wellbeing of participants. Psychological detachment from work, a key indicator of work-life balance, rose by 22.5 percent. Overall wellbeing increased by 21 percent, while sleep problems were reduced by 20 percent.

Perceived stress decreased by 8.6 percent, and sleep quality improved by 6.2 percent. Emotional exhaustion burnout dropped by 14.7 percent, and depersonalisation burnout saw a slight decline of 2.3 percent. Feelings of personal accomplishment rose by 11.4 percent. Anxiety symptoms showed a reduction of 5 percent, with additional declines noted in stress and depression levels.

“The results speak for themselves”, said Dr. Charlotte Rae, Research Lead, University of Sussex. “These significant improvements in areas related to physical and mental wellbeing demonstrate the transformative power of a four-day work week. Improved sleep quality and reduced stress and exhaustion are factors that could have a significant impact on our health, with the potential to enhance our lives in- and outside of work. This study provides further compelling evidence for the benefits of flexible working models.”

Productivity Outcomes and Impact on Customer Service

Despite a reduction in working hours, task execution remained consistent. Staff reported a 19.4 percent increase in goal attainment and a 9.3 percent rise in self-efficacy, with greater confidence in achieving work objectives and an improvement in goal attainment compared to before the trial period.

While productivity metrics were generally positive, there were some challenges in maintaining consistent customer service levels, as the wider British public expect the same level of service throughout the traditional five-day working week. This prompted Thrive to consider a seasonal implementation of the four-day work week moving forward.

“Our four-day work week trial revealed incredibly encouraging results and we saw a fantastic impact on the people within our business,” commented Cassie Gasson, Co-CEO, Thrive. “While we would have loved to implement it on a full-time basis, our experiences in the trial also highlighted that the success of a four-day work week will rely on widespread cultural change across the UK business landscape. As a business serving hundreds of organisations, it highlighted that five-day coverage for our customers is essential when they’re operating more traditional ways of working.

“New flexible working guidelines are a positive start, but the UK government should consider implementing policies which could help make a four-day work week a reality. This will enable more modern businesses that are ready to adopt this transition to do so. The benefits are evident through its potential to boost business productivity, increase wellbeing, and generally make the country happier and healthier and the UK has the potential to take the lead on this by pioneering the four-day work week and reaping the rewards.

“Until then, it’s difficult for us to commit full time and will look at a more flexible seasonal approach to support the great benefits proven.”