For a hundred years, most people have worked five days a week. Now some companies are trying something new. They give their staff a free day every week but pay them the same money. Workers must finish the same amount of work in four days instead of five. People call this the four-day week.

A small design company in Hanoi tried it for six months. The boss, Ms Linh, was worried at first. But her team cut their meetings from ten hours a week to three, and they turned off their email for two hours every morning. In the end, the company finished the same number of projects.

The staff were happier too. They slept longer, and fewer people were ill. Many of them used the free day for family or for a doctor's visit, so they did not need to leave work early on other days. Two workers said they felt tired in a new way, because four days were very busy.

However, the idea does not fit every job. An office can cut meetings, but a hospital cannot cut patients. A shop must open when customers come, and a factory machine must run. In these places, a four-day week means hiring more people, and that costs money. So the new week may spread in offices first, and slowly, if at all, in other jobs.