As people perform monotonous tasks, their brain shifts towards an at-rest mode whether they like it or not, researchers discover.

And by monitoring that area of the brain, researchers can predict when someone is about to make a mistake before they make it, according to their study in the Proceedings of the National Academy of Sciences.

Human errors are, therefore, not the result of momentary blips in brain activity or concentration, as some suspect, the researchers say.

"There's this thing that's probably intrinsic where your brain says I do need to take a little break here and there's nothing you can do about it," says author Dr Tom Eichele of Norway's University of Bergen.

When that happens, blood flows into the part of the brain that is more active in states of rest.

And since this state begins about 30 seconds before you make a mistake, it could be possible to design an early warning system that could alert people to be more focused or more careful, Eichele says.