Patients that wake during surgery can experience mental health problems as a result, warn researchers.
US researchers looked at a cohort of 2,681 patients who underwent general anaesthetic, and interviewed 46 subjects who considered themselves to be aware during their procedure.
The authors found that 20 of the patients had experienced pain and 30 described acute emotional reactions during the awareness episode.
But they also said that 15 patients experienced late psychological symptoms, which lasted more than two months in six cases. One patient was later diagnosed with post-traumatic stress disorder.
Anesthesiology (2007) 106: 26-32