Out-of-body experiences in relation to lucid dreaming and sleep paralysis: a theoretical review and conceptual model

Abstract

Out-of body experiences (OBEs) are characterized by the subjective experience of being located outside the physical body. Evidence supports that OBEs triggered by electrical stimulation and epileptic seizures are associated with disrupted brain activity in a distributed network centred at the temporo-parietal junction and the resulting multisensory disruption of body representation. However, little is known about the neurophysiology of spontaneous OBEs, which are often reported by healthy individuals as occurring during states of reduced vigilance, particularly in proximity to or during sleep (sleep-related OBEs). A sleep phenomenon that has been linked to this particular kind of OBE is lucid dreaming, i.e., the realization of being in a dream state. Thus, both lucid dreams and sleep-related OBEs are characterized by the conscious awareness of not being in a standard waking state at the moment of the experience. In this paper, we review the current state of research on sleep-related OBEs and hypothesize that these phenomena, along with certain types of lucid dreams, are more likely to occur during direct transitions from wakefulness to REM sleep (sleep-onset REM periods). Based on this hypothesis, we propose a new conceptual model that potentially describes the relationship between OBEs and sleep states. The model sheds light on the phenomenological differences between sleep-related OBEs and similar states of consciousness, such as lucid dreaming and sleep paralysis, and explores the potential polysomnographic features underlying sleep-related OBEs. Subsequently, we apply the predictive coding framework to suggest that sleep-related OBEs form part of a broader spectrum of experiences, proposing a connecting link between OBEs occurring in a sleep state and OBEs reported during wakefulness. We conclude by discussing experimental options for testing this model.