But despite the vast volumes of data that have been gathered over the years, the medical profession still insists on interns working shifts in excess of 24 hours. Inevitably they start making mistakes, sometimes life-threatening ones.

A new study confirms the problems, and no doubt will be added to all the previous ones that painted the very same picture. One of the earlier studies, published 33 years ago, found that interns made almost twice as many errors reading electrocardiograms after an extended shift than if they had had a proper night's sleep.

Since then, nothing has been done to change what is a ludicrous work pattern, and one that endangers lives. The new study found that interns made 22 per cent more serious mistakes after a 'traditional schedule', where they had worked for at least 24 hours without sleep, than if they had worked an 'intervention schedule', where they worked a normal day and slept. They also made 20 per cent more medication errors - either prescribing the wrong dose or the wrong drug - and nearly six times more diagnostic errors during the traditional schedule.

(Source: New England Journal of Medicine, 2004; 351: 1838-48).