The Spanish government is considering reducing the official work week to four days, Bloomberg reported. The news comes right on the heels of Unilever's New Zealand branch launching an experiment with a four-day work week as well. But while the New Zealand experiment is focused on effects to worker morale and productivity, the Spanish government is considering the measure to boost employment.

A shortened work week to boost job growth is an idea going back many decades. In 1981, a German study found that reducing weekly work hours by 5 percent would lead to a 3.6 percent increase in employment if hourly pay remained unchanged, and a 4.4 percent increase if workers were compensated for lost wages. Far more recently, a report from the International Labor Organization said that "cutting hours of work can have positive effects on employment levels during a severe economic downturn," and that "permanent reductions in working hours have generally, though not always, shown net positive employment effects." The idea is that companies would expand hiring more quickly under such a compressed schedule. Yet the ILO report said that the effectiveness of such a policy depends on how it is implemented with regard to factors such as flexibility in the volume and patterns of hours reductions. A 1999 report by the International Monetary Fund came to a similar conclusion, saying that just straight up reducing the work week actually carries negative effects of employment, but if "the reduction in hours is accompanied by policies that serve to counteract the negative impact of the hours reduction on employment, then employment may be increased."

Beyond macroeconomic effects, other studies have found that employees generally like a shorter work week (shock of shocks): People who've tried it find themselves less stressed, better able to manage work-life balance and overall enjoying work more.

While some are skeptical about a four-day work week, believing that it creates a productivity disaster, such concerns are hardly new. A journal article from 1919 noted that British textile manufacturers greatly protested even reducing the work day from 12 hours to 10, saying it would kneecap productivity to the point where investments in the industry would no longer be worth it. In The Quest for Time, which outlines international movements for an eight-hour workday in the 19th and early 20th century, author Gary Cross says that there was vicious resistance in France to a bill mandating one half-day off of work per week for women, with 10 of 28 local chambers of commerce formally opposing the measure; opponents thought it was an unwelcome intrusion into how they ran their businesses and said it would increase costs in the long run from having to hire more workers.