Intraoperative dreams reported after general anaesthesia are not early interpretations of delayed awareness

Abstract

Dreams are more frequently reported than awareness after surgery. We define awareness as explicit recall of real intraoperative events during anaesthesia. The importance of intraoperative dreaming is poorly understood. This study was performed to evaluate whether intraoperative dreams can be associated with, or precede, awareness. We also studied whether dreams can be related to case-specific parameters. A cohort of 6991 prospectively included patients given inhalational anaesthesia were interviewed for dreams and awareness at three occasions; before they left the post-anaesthesia care unit, days 1-3 and days 7-14 after the operation. Uni- and multivariate statistical relations between dreams, awareness and case-specific parameters were assessed. Two hundred and thirty-two of 6991 patients (3.3%) reported a dream. Four of those also reported awareness and remembered real events that were distinguishable from their dream. Awareness was 19 times more common among patients who after surgery reported a dream [1.7% vs. 0.09%; odds ratio (OR) 18.7; P=0.000007], but memories of dreams did not precede memories of awareness in any of the 232 patients reporting a dream. Unpleasant dreams were significantly more common when thiopentone was used compared with propofol (OR 2.22; P=0.005). Neutral or pleasant dreams were related to lower body mass index, female gender and shorter duration of anaesthesia. We found a statistically significant association between dreams reported after general anaesthesia and awareness, although intraoperative dreams were not an early interpretation of delayed awareness in any case. A typical dreamer in this study is a lean female having a short procedure.