Another response from one of my colleagues, Davis Lukoff:
Nonordinary States of Consciousness in Transpersonal Psychotherapy
William James first explored how nonordinary states of consciousness can be induced and the value that they have for providing access to special knowledge that cannot be gained through ordinary consciousness. Many schools of psychology “adhere to an unnecessarily restricted view of the psyche [and refuse to] work therapeutically with spiritual experience and experiences of nonordinary reality” (Scotton, 1996, p. 3). In transpersonal psychotherapy, induction of nonordinary states of consciousness has a respected place.
Transpersonal psychotherapists have explored the healing potential of many states of consciousness, including those associated with meditation, bodywork, movement, dreamwork, guided imagery, prayer, drumming, chanting, sweat lodges, fasting, shamanic journeying, and psychedelic drugs (Cortright, 1997). Anthropologist Michael Hamer (1990) and Native American psychologist Leslie Gray (2002) have developed shamanic counseling approaches based on shamanic practices that induce nonordinary states (particularly drumming). New techniques to induce nonordinary states have also been developed such as holotropic breathwork, an experiential procedure developed by Stanislav and Christina Grof involving several-hour sessions of music, energy work, and hyperventilation to simulate psychedelic drug experience (K. Taylor, 2003).