Brachial artery endothelial function in residents and fellows working night shifts.

Brachial artery endothelial function, which is measured as responsiveness to reactive hyperemia (flow-mediated dilation [FMD]) was abnormal in residents and house staff after a 24-hour shift, including night duty. The greatest decrease in FMD was observed in physicians with a longer history of night-shift duty and in those reporting fewer sleeping hours during the shift. The finding that FMD is decreased after night duty raises the issue of the effects of shift duty on cardiovascular function in healthcare personnel, particularly in those undertaking night duty for a prolonged period of time.