Consciousness in non-REM-parasomnia episodes.

Non-REM sleep parasomnias like sleepwalking and sleep terrors involve a variable spectrum of consciousness, not just automatic or unconscious behavior. In interviews with 35 adult patients, consciousness during episodes ranged from minimal or absent (frequently or always present in 36%) to preserved conscious experiences with delusional thinking (65%), hallucinations (53%), impaired insight (77%), negative emotions (75%), and variable amnesia (30%). Patients described feeling as if they were in a dream while awake, a state termed "awake dreaming." Surroundings could be perceived realistically, misinterpreted, or entirely hallucinated, depending on the delusion. These findings suggest that consciousness, amnesia, and sensory disconnection during episodes are graded and variable, and full-fledged experiences share core features of dreams, offering a model for studying consciousness and sensory disconnection.

Study at a glance

Abstract

Sleepwalking and related parasomnias are thought to result from incomplete awakenings out of non-rapid eye movement (non-REM) sleep. Non-REM parasomnia behaviours 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 characterise the full spectrum of consciousness and environmental (dis)connection associated with behavioural 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 behaviours (frequently/always present in 36% of patients) to preserved conscious experiences characterised 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"). The 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, amnesia and sensory disconnection during non-REM parasomnia episodes 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.