Extreme tiredness and exhaustion among NHS staff poses a significant risk to patients, England's NHS safety watchdog warns.
The Health Services Safety Investigations Body said medication errors, impaired decision-making, reduced attention and rude and disrespectful behaviour were the most common problems associated with fatigued staff in hospitals.
It said there was limited data on the scale of the problem, but cited evidence from staff surveys and information provided by safety experts that it was a contributory factor in safety incidents.
In its report, the watchdog gave examples of mistakes being made with pregnancy scans and chemotherapy drugs.