Neural and Experiential Dynamics of High-Ventilation Breathwork Mirror Psychedelic States

High-ventilation breathwork (HVB) is a simple breathing technique that nevertheless frequently triggers experiences resembling psychedelic states. While recent studies have begun to pinpoint physiological and neural changes involved in altered states of consciousness (ASCs) evoked by HVB, the interplay between neural and experiential dynamics throughout an HVB session remains unclear. Here we tracked neural activity (via 64-channel EEG recordings) as well as subjective experience depth and content in 25 experienced HVB practitioners across resting-state recordings interleaved throughout a naturalistic HVB session. We find that neural dynamics evoked by HVB emulate the most robust neural signatures of classical psychedelic states, specifically (1) loosening of temporal structure, including broadband cortical desynchronization, increased signal complexity, and decreased oscillatory power in the Alpha (8 - 13 Hz) range, and (2) reorganization of spatial structure, including a flattening of cortical processing hierarchy. These neural effects directly correlated with participants subjective depth with minute resolution, but were not explained by isolated features of HVB such as music listening or active interoception. Together, these results identify unifying neural features of psychedelic-like ASCs regardless of induction method, demonstrating that cortical states triggered by psychedelics can also be accessed by non-pharmacological routes, and breathwork is a powerful way to do so.