Brain electrical activity and subjective experience during altered states of consciousness: ganzfeld and hypnagogic states.
International Journal of Psychophysiology November 2002 Jirí Wackermann, Peter Pütz, Simone Büchi et al.
Manifestations of experimentally induced altered states of consciousness in the brain's electrical activity as well as in subjective experience were explored via the hypnagogic state at sleep onset, and the state induced by exposure to an unstructured perceptual field (ganzfeld). Twelve female paid volunteers participated in sessions involving sleep onset, ganzfeld, and eyes-closed relaxed...