Scans shed light on changes in brain when we zone out while tired

Study finds lapses of attention in sleep-deprived people coincide with wave of fluid flowing out of the brain

It's never a great look. The morning meeting is in full swing but thanks to a late night out your brain switches off at the precise moment a question comes your way.

Such momentary lapses in attention are a common problem for the sleep deprived, but what happens in the brain in these spells of mental shutdown has proved hard to pin down.