TOKYO (BLOOMBERG) - After spending August experimenting with a four-day work week in a country notorious for overwork, Microsoft Japan said sales per employee rose 40 per cent compared with the same month last year.

The "Work-Life Choice Challenge Summer 2019" saw full-time employees take off five consecutive Fridays in August with pay, as well as shortening meetings to a maximum of 30 minutes and encouraging online chats over face-to-face ones.

Among workers responding to a survey about the programme, 92 per cent said they were pleased with the four-day week, the software maker's Japan affiliate said in a report on its website on Oct 31.

Japan has been struggling to bring down some of the world's longest working hours as it confronts a labour shortage and rapidly ageing population.

Japanese Prime Minister Shinzo Abe's push to make workplaces more flexible and reduce overtime has drawn mixed reviews.

The summer trial also cut costs at Microsoft Japan, with 23 per cent less electricity consumed and 59 per cent fewer pages printed compared with August 2018, according to the report.

Some Microsoft Japan managers still did not understand the changes in working styles and some employees expressed concern that shorter work weeks would bother clients.

Microsoft Japan plans to hold another work-life challenge in winter.

Employees will not get special paid days off, but will be encouraged to take time off on their own initiative "in a more flexible and smarter way."