Microsoft Japan said sales per employee, a metric of productivity, surged 40 per cent after running a month-long experiment that saw full-time employees work a four-day week.
The tech company's Work-Life Choice Challenge Summer 2019 initiative saw offices closed for five consecutive Fridays in August with staff still paid their full salaries. Meetings were also shortened to 30 minutes and employees were encouraged to communicate online rather than face to face.
The study was carried out "to help corporate customers reform work styles", Microsoft Japan said.
The summer experiment was given a favourable response by 92 per cent of the Microsoft staff surveyed after the event.
As well as improved staff sentiment, the company also reduced its costs, with electricity consumption falling 23 per cent and paper printing dropping 59 per cent compared with August 2018, Microsoft said.
Global studies into working hours suggest the longer your working day, the greater the risk of health problems such as depression and heart failure to premature death.
A June study carried out in France by Angers University and the French National Institute of Health and Medical Research found that people working long hours had a 29 per cent greater risk of stroke. The study examined data on age, smoking and working hours of more than 143,000 adults and found just under a third worked long hours, with 10 per cent working long hours for 10 years or more.
Meanwhile, employees working 40 to 55 hours per week have a higher risk of stroke compared with those working standard hours of 35 to 40 hours, according to a 2015 study of 60,000 people published in the British medial journal The Lancet.
Overworking has been well documented in Japan, where "karoshi" means death from overwork. A 2016 white paper published by the Japanese government found that one in five Japanese workers were at risk of death from overwork. In April, the Japanese government’s new work reform law came into effect, limiting overtime to 45 hours per month.
Despite the positive results of the Microsoft Japan study, the technology company said it was planning to run a second Work Life Choice Challenge this winter but would not be offering the same "special leave".
Instead, staff are encouraged to "rest smartly", do their work in a shorter amount of time and take advantage of shorter 30-minute meetings.
"An internal contest will be held to recruit ideas for how to work, rest and learn this winter," the company said.
When it comes to the countries working the longest hours, Japan is not the worst offender. Mexicans work longer than people in any other country, according to 2019 data from the Organisation for Economic Co-operation and Development, clocking up an average 2,148 hours at work per year per employee. In Japan, however, the average worker does 1,680 hours per year – below the OECD average of 1,734.