In 1929, the Soviet Union replaced the seven day week with the nepreryvka or “continuous working week”. Workers were split into five groups on five-day cycles with staggered rest days so that production never stopped. It became common for people to colour-code their friends in their address books according to which day they had off.

It wasn’t popular. “What is there for us to do at home, if our wives are in the factory, our children are at school and nobody can visit us?” one worker complained in a letter to a newspaper. As Oliver Burkeman, who writes about the nepreryvka in his new book Four Thousand Weeks, observes: “The value of time comes not from the sheer quantity you have, but from whether you’re in sync with the people you care about most.”

The Soviet Union abandoned its vast experiment after 11 years. But today’s economy is moving back towards a sort of “continuous working week”. Society’s shared rhythms of daytime work and weekend rest are disintegrating before our eyes.