A study of 45 German companies by 4 Day Week Global (4DWG) took a widespread view of the benefits of a four-day week, with previous studies focusing on things like company revenue, attrition, and perceptions of burnout.  

The headline results were in line with what we have come to expect from four-day workweek trials. Researchers found average revenues among participant companies increased by 36% compared with the previous year, a 42% decrease in employee resignations, and a 64% reduction in burnout.

However, unlike other widespread four-day workweek trials, which focused solely on employer and employee surveys, researchers for the German trial took a more holistic approach that considered participants’ underlying health. 

One unique approach involved collecting 277 hair samples in the first wave of the study to gauge participants’ cortisol levels, which helps measure stress in the body. The results of that study are yet to be disclosed.

What researchers did discover, however, was that participants of the four-day workweek trial were sleeping more than their five-day peers. Workers in the trial got an average of 38 minutes more sleep per week. They also registered an extra 25 minutes of physical activity each week.

These combined benefits appear to have had a notable effect on stress levels, which fell by nearly 90 minutes a week among participants. 

There is hope that the wider rollout of a four-day workweek could help reduce the negative business effects of wellbeing issues like rising burnout, which leads to sick leave. One of the major expectations in the 4DWG trial was a reduction in sick leave among staff.

German bosses have lamented the country’s high level of sickness-related absence from work, which is much higher than other European countries. 

The average German worker took 15 days of sick leave in 2023, while the country’s largest health insurance provider, Techniker Krankenkasse (TK), found that insured workers took an average of 19.4 sick days last year. 

The German Association of Research-Based Pharmaceutical Companies (VFA) found that above-average levels of sick leave in Germany cost the country €26 billion last year, causing it to contract rather than expand.

However, the findings from 4DWG didn’t find a statistically significant difference in the number of sick days taken between workers on a four-day week and those on a five-day week.

Four-day workweek?

The results of the latest trial need to be taken with a pinch of salt.

Typical four-day week trials follow the 100:80:100 rule, where workers receive 100% of their pay for 80% of their regular hours while delivering 100% productivity. 

Among the trial participants, only a third reduced their working hours by 20% a week. Another fifth cut their working hours by between 11% and 19%, while around half reduced their hours by less than 10%, or up to four hours a week. 

The U.K.’s Labour government launched the first official four-day week trial this week, where 1,000 workers are set to experiment with its potential benefits. The trial comes alongside a new flexible work bill, giving employees the right to demand a four-day week from their company.

A previous U.K. trial labeled the largest ever was seen as a huge success, with seven out of 10 workers reporting a drop in burnout levels without their employers experiencing falling revenues.