Boring jobs turn our mind to autopilot, say scientists - and it means we can seriously mess up some simple tasks.

Monotonous duties switch our brain to "rest mode", whether we like it or not, the researchers report in Proceedings of National Academy of Sciences.

They found mistakes can be predicted up to 30 seconds before we make them, by patterns in our brain activity.

The team hopes to design an early-warning brain monitor for pilots and others in "critical situations".

The scientists say the device would be particularly suitable for monotonous jobs where focus is hard to maintain - such as passport and immigration control.

Mistakes 'foreshadowed'

"We might be able to build a device (that could be placed) on the heads of people that makes these easy decisions," said Dr Eichele, of the University of Bergen, Norway.

"We can measure the signal and give feedback to the user that your brain is in the state where your decisions are not going to be the right one."