The jury is still out on the four-day week

Too much has been made of one short experiment, but there's no doubt the the world of work is changing
Blonde businesswoman with glasses using laptop while stroking her chin. Getty Images

In his 1930 essay Economic possibilities for our grandchildren, the British economist John Maynard Keynes shared his vision of what our working lives might look like a century down the line. "We shall endeavour to spread the bread thin on the butter − to make what work there is still to be done to be as widely shared as possible," he wrote. "Three-hour shifts or a 15-hour week may put off the problem for a great while."

That future might not have yet become a reality but, thanks to developments in artificial intelligence and the changing nature of the modern workplace, the question of how long the standard working week should be is now more pertinent than ever. According to the World Economic Forum's latest Future of Jobs report, by 2022, up to 75 million positions could be lost to automation globally. However, the media has recently concentrated on another far more palatable story.

Lately, the idea of a four-day working week has been the topic of intense interest. The New Zealand-based company Perpetual Guardian − which manages trusts, wills and estate planning for its clients – trialled this model between March and April this year. During that period, its 240 employees worked 32 hours a week over four days, instead of 40 hours over five days, with no reduction in salary. Academic researchers collected qualitative and quantitative data throughout the experiment. In light of the positive results, including lower self-reported levels of stress, greater engagement and improved performance, the company decided to implement the change permanently.

Over the years, a number of scientific studies have hinted at the benefits of working fewer hours. In 2015, for instance, an article in the Lancet reported results of what is arguably the largest research project on the relation between working hours and the risks of stroke and coronary heart disease. Published and unpublished data collected on 603,838 individuals across Europe, Australia and the US was analysed, revealing that the more hours one works, the higher the risk for stroke and heart disease.

Meanwhile, a 2013 study published in the International Archives of Occupational and Environmental Health came to a conclusion that will be obvious to many of us: that levels of cortisol − a steroid hormone associated with stress – were higher among subjects when they were at work and lower on their days off.

It is, however, intriguing that a single eight-week trial conducted by one company in New Zealand should prompt such widespread support for the universal roll-out of a four-day working week, especially considering how short it was. Studies on the benefits of reducing work weeks to four days are not a new thing, by any means. The Journal of Nursing Administration carried an article on this very topic back in 1971. Trials over longer periods of time have also been undertaken in Sweden and Iceland over the past four years. They yielded results worthy of further attention − ranging from less sick leave to improved productivity − but none that could be taken as a general rule, outside the specific working cultures and business sectors studied.

As always, there is no one-size-fits-all solution. Trials are necessary to inform policy and strategy. However, they must be performed over an adequate period of time to ensure that their results are not merely temporary blips. In addition, self-reporting should not be relied on too heavily. After all, research consistently shows gaps between what people report and what is really happening.

Clear neurophysiological data must be collected to assess the impact of changes to working hours on the health of workers, especially the effects of stress. When rigorous data shows the long-term benefits of a four-day work week, I will be all for it, but I am against generalising on the basis of one short-term experiment.

Still, we do appear to be moving in that direction. In a blog post published on his company's website earlier this year, Richard Branson, founder of the Virgin Group, wrote: "By working more efficiently, there is no reason why people can't work [fewer] hours and be equally – if not more – effective. People will need to be paid more for working less time, so they can afford more leisure time. That's going to be a difficult balancing act to get right, but it can be done." Here, Mr Branson sounds very much like one of the grandchildren that Keynes imagined.

Professor Olivier Oullier is the president of Emotiv, a neuroscientist and a DJ