Trance states during a mind-body intervention monitored by BIS

Mind-body interventions are increasingly used in health care, both for physical and for psychological therapy. With directing the focus to the body and inner experiences they include elements of trance induction and hypnosis. The scope of this experimental study was to test the hypothesis that a non-ordinary state of consciousness may occur during a mind-body intervention with changes in electrical brain activity similar to a hypnotic induction.

Bispectral Index an EEG-derived parameter used in anesthesia, was monitored during a test of hypnotic susceptibility including a trance induction, and during a mind-body intervention modified from the Feldenkrais method. 54 adult volunteers were tested with a short version of the Harvard Group Scale of Hypnotic Susceptibility (HGSHS-5) and the instructions for a mind-body intervention from a 30-min audio file. The latter consists of an introduction, reflections on posture and sensations, and four suggested tasks with body movements and variations followed by a break each time. Contributing factors, namely age, sex, suggestibility and daytime, were analyzed by multifactorial analysis and linear regression.

BIS significantly decreased from an awake value of 97.5 to values of 88-92, similar in extent to the hypnosis induction of the test for HGSHS-5. Besides a general decline with duration significant drops were observed with every break. None of the tested potential influencing factors had significant impact.

Measurable changes in electrophysical brain activity can be detected during a mind-body intervention as a surrogate marker of a state of non-ordinary consciousness. The high relevance arises from the fact that inclusion of the unconscious is essential for initiating beneficial changes in psychological and physical patterns, as these patterns are encoded and maintained there. The EEG reactions and aspects of a focus shift toward inside, body scan and confusion bring it close to hypnotic trance and provide new and objective research approaches.