Taking a quick nap at your desk or even in a meeting is not an uncommon sight in Japanese offices, but it's something you're unlikely to find in Britain, where workers are expected to remain alert at all times.

In Japan, the practice is known as inemuri — taking a short nap when you are officially supposed to be doing something else. It is often permitted because it shows you have been working hard and are just taking a little time out.

Brigitte Steger, a senior lecturer in modern Japanese studies at Cambridge University, has been studying the habit and has written extensively on the practice. Inemuri also applies to nonwork contexts, such as when people fall asleep on the train or on social occasions.