[Uncertain if physicians' shift work causes patient harm].

The role of physicians' shift work in adverse events causing patient harm is not clear. However, extended shifts reduce psychomotor performance and cognition in daytime after a 24-hour shift. The incidence and preventability of adverse events in Denmark are comparable to other Western countries, despite the fact that Danish physicians do not work extended hours. The role of physicians' shift work in adverse events causing patient harm remains controversial and further research is needed.