Consciousness Beyond the Brain: The Role of the Autonomic Nervous System in Non-ordinary States of Consciousness

Non-ordinary states of consciousness (NOSCs), whether entered via psychedelics, breathwork, hypnosis or other means, show striking therapeutic promise by improving well-being and reducing psychopathology across diverse conditions. While the neuronal dynamics underpinning such therapeutic shifts in consciousness have to some extent been mapped, research has mainly focused on the central nervous system (CNS). In contrast, the contribution of the autonomic nervous system (ANS) to NOSCs remains largely unexplored. At the same time, growing evidence indicates that beyond simply regulating bodily functions, the ANS mediates a range of processes directly linked to the core effects of many NOSCs, from emotional regulation to interoception and cognitive function.In this review, we delineate the potential role of the ANS in shaping NOSCs, and discuss pathways by which ANS responses may support the cortical dynamics associated with NOSCs. Based on these insights, we propose a framework whereby inducing physiological stress within a conducive context supports the emergence of NOSCs, and the coexistence of high arousal and relaxation, i.e. of both sympathetic and parasympathetic tone, serves a hallmark of peak NOSCs. Finally, we highlight opportunities for future research to pinpoint these dynamics further, and offer an outlook on how understanding the ANS dynamics linked to NOSCs can allow us to induce NOSCs more safely, optimize their therapeutic impact, and provide cost-effective yet powerful physiological tools to monitor and facilitate these states in real time.