Yoga nidra, an ancient meditative practice, induces an altered state of consciousness distinct from sleep. In a preliminary study, six healthy volunteers completed 12 guided sessions during a retreat. EEG recordings showed no sleep markers (K-complexes or spindles) during practice. Compared to a resting baseline, participants reported increased dissociative effects, altered body image, reduced rational thinking, and less volitional thought control. One subject's EEG analysis revealed early increases in alpha, beta, and theta power followed by reductions, with gamma power rising in later stages. These findings suggest yoga nidra produces a unique psychophysiological state, though larger studies are needed.
Long-term meditation practice alters connectivity within two key resting-state brain networks: the default mode network (DMN) and the salience network (SN). Experienced meditators show enhanced self-referential processing in the DMN and reduced reactivity in the SN, suggesting that meditation refines attentional control and internal awareness. The study used dynamic causal modeling for EEG to analyze effective connectivity in a unique monastic population—monks and geshes from the Tibetan University of Sera Jey in India. These findings provide new insights into the neurophysiological mechanisms underlying long-term meditation and highlight monastic practitioners as a valuable model for studying experience-related brain changes.
Advanced meditation in experienced Tibetan monks produces a unique psychophysiological state of relaxed-vigilance, characterized by enhanced parasympathetic tone, decreased respiratory rate, and gradually increasing electrodermal activity—indicating simultaneous calm and alertness. EEG recordings showed elevated gamma-band power during analytical meditations. These findings suggest that advanced meditative practices foster an adaptive integration of autonomic and cortical responses, supporting well-being and cognitive flexibility.