Non-REM parasomnia experiences share EEG correlates with dreams

Sleepwalking and related parasomnias result from sudden and incomplete awakenings out of slow wave sleep. Clinical observations suggest that behavioral episodes can occur without consciousness and recollection, or in relation to dream-like experiences. To understand what accounts for these differences in consciousness and amnesia, we recorded parasomnia episodes with high-density EEG and interviewed participants immediately afterwards. Compared to reports of unconsciousness (19%), reports of conscious experience (81%) were preceded, during prior sleep, by high-amplitude slow waves in anterior cortical regions and an activation of posterior cortical regions. Reduced posterior slow wave activity was also present during the episode when patients displayed elaborate behaviours in relation to dream-like scenarios. Amnesia for the experience (25%) was modulated by right medial temporal activation during prior sleep and fronto-parietal slow wave activity during the episode. Thus, the neural correlates of parasomnia experiences are similar to those previously reported for dreams and therefore likely reflect core physiological processes involved in sleep consciousness.