The expression ‘trance state’ covers a rather wide field. The mediumistic trance and the self-induced trance, as well as various degrees of awareness expansion, may be classified as ‘trance states’. However, the more common and more spectacular ritual trance, which is probably the trance to which you refer, is achieved through cultural cues, ritual props, incantations, songs and stories. Percussive music, steady musical pulse, is especially important in the transition to altered states in cultures throughout the world. The most effective rhythm is through electrically stimulated acupuncture. It matches the EEG frequency of theta waves, which are produced by the brain during periods of deep meditation but appear only rarely in a normal waking state. Faith Healers have been show to produce continuous theta waves in their patients by the laying on of hands, and the patients; theta waves exactly match the pattern of the Faith Healers’ wave.