Working overtime doesn’t increase your output. It makes you stupid.
Arianna Huffington talks often about how the key to her productivity is sleep.
It’s a smart suggestion, not least because so many of us still imagine that the more we work, the more productive we are. For over a hundred years or more, this has been deemed nonsense.
The first productivity studies were conducted by Ernst Abbe at the Zeiss lens laboratories in the 1880s. They indicated what every other productivity study has shown since: that, up to around 40 hours a week, we’re all pretty productive but, after that, we become less able to deliver reliable, cost-effective work. Why? Because when we get tired, we make mistakes—and the extra hours we put in are absorbed by correcting our errors. This is demonstrably true in industries like software coding, in which mistakes can cost a lot of time to put right. But it is equally true in manufacturing where more units of production also mean more flaws and waste.