Slow nasal breathing selectively modifies state of consciousness in healthy humans: a psychometric study

Introduction: Neurophysiological studies in animal models and in humans revealed that mechanical stimulation of olfactory epithelium via odourless air synchronizes neuronal rhythms in cortical and subcortical areas. A study from our group found that “passive” ultra-slow mechanical stimulation of olfactory epithelium alters the state of consciousness in healthy subjects by slowing cerebral rhythms in higher-order areas (e.g. Default Mode Network). The aim is to investigate the role of “active” (i.e. guided by top-down attention) slow nasal breathing on consciousness states. Methods: Sixteen healthy volunteers, with a mean of 1700 hour of Pranayama practice, performed 15 min of Samavritti Pranayama at 2.5 b/min through the nose. As control condition, the same session was performed breathing only through the mouth. Before and after each session, the state of consciousness was measured through the Clinician Administered Dissociative States Scale and the Phenomenology of Consciousness Inventory. Data were analysed with a two-factor (pre/post, nose/mouth) repeated measures ANOVA. Results: Only nasal breathing increased dissociative state (p<0.01) and altered the state of consciousness (p<0.01), with increased introspection (p<0.01) and altered body perception (p<0.05). Conclusions: A breathing-related nasal mechanical stimulation specifically leads to meditative-like, altered state of consciousness.