Conclusions
Our findings support the hypothesis that anaesthetic-induced unresponsiveness and NREM sleep are both characterised by disconnected conscious experiences with highly similar recall frequencies and content. These findings align with the mechanistic and neurophysiological similarities between anaesthetic-induced unresponsiveness and NREM sleep. Although anaesthetic-induced unresponsiveness in an experimental setting is not comparable with surgical anaesthesia and rather corresponds to moderate sedation, our results have relevance for clinical practices, both for sedation and surgical anaesthesia. We speculate that in some cases surgical anaesthesia does not represent a state of unconsciousness, but that patients disconnected from the environment might experience internally generated experiences similar to those experienced under NREM sleep. This poses no problem for successful surgical anaesthesia as long as patients remain disconnected from and unaware of external and bodily stimuli.