Gruelling, long shifts may not have the effect on medical errors in hospitals as thought, with new findings pointing towards workload as the important factor.

The multi-hospital study on the effect of sleeplessness on medical errors by intensive doctors care shows how complex the issue of working hours and medical errors has become, the US researchers say.

They found ICY doctors who were forced to work 24-hour shifts made fewer serious medical mistakes – to the tune of 53% – than their counterparts assigned to schedules without extended shifts.

But the trial also found the doctors who worked fewer consecutive hours were responsible for 31% more paediatric ICU patients than those in the extended-shift group.