Consciousness in Non-REM parasomnia episodes

Abstract

Sleepwalking and related parasomnias are thought to result from incomplete awakenings out of Non rapid eye movement (Non-REM) sleep. Non-REM parasomnia behaviors have been described as unconscious and automatic, or related to vivid, dream-like conscious experiences. Similarly, some observations have suggested that patients are unresponsive during episodes, while others that they can interact with their surroundings. To better grasp and characterize the full spectrum of consciousness and environmental disconnection associated with behavioral episodes, 35 adult patients with Non-REM sleep parasomnias were interviewed in-depth about their experiences. The level of consciousness during parasomnia episodes was reported to be variable both within and between individuals, ranging from minimal or absent consciousness and largely automatic behaviors (frequently/always present in 36% of patients) to preserved conscious experiences characterized by delusional thinking of varying degrees of specificity (65%), often about impending danger, variably formed, uni- or multisensory hallucinations (53%), impaired insight (77%), negative emotions (75%) and variable, but often pronounced amnesia (30%). Patients described their experiences as a dream scene during which they felt awake ( awake dreaming). Surroundings were either realistically perceived, misinterpreted (in the form of perceptual illusions or misidentifications of people) or entirely hallucinated as a function of the prevailing delusion. These observations suggest that the level of consciousness and sensory disconnection in Non-REM parasomnias is variable and graded. In their full-fledged expression, Non-REM parasomnia experiences feature several core features of dreams. They therefore represent a valuable model for the study of consciousness, sleep-related sensory disconnection and dreaming.