Clinical hypnotherapy induces an altered state of consciousness, or trance, for therapeutic intervention. All hypnotic states are characterized by a pleasant state of relaxation, which allows individuals to enter so beneficial suggestions may be given directly to the subconscious. Under hypnosis, the conscious, rational part of the brain is temporarily bypassed, making the subconscious part, which influences mental and physical functions, receptive to therapy. During the trance state there is heightened concentration for the specific purpose of maximizing potential, changing limiting beliefs and behaviours and gaining insight and wisdom. In 2003, a meta-analysis of the efficacy of hypnotherapy was published by two researchers from the university of Konstanz in Germany, Flammer and Bongartz. The study examined data on the efficacy of hypnotherapy across the board, though studies included mainly related to psychosomatic illness, test anxiety, smoking cessation and pain control during orthodox medical treatment. Most of the better research studies used traditional-style hypnosis, only a minority (19%) employed Ericksonian hypnosis.
The authors considered a total of 444 studies on hypnotherapy published prior to 2002. By selecting the best quality and most suitable research designs for meta-analysis they narrowed their focus down to 57 controlled trials. These showed that on average hypnotherapy achieved at least 64% success compared to 37% improvement among untreated control groups. (Based on the figures produced by binomial effect size display or BESD.)
According to the authors this was an intentional underestimation. Their professed aim was to discover whether, even under the most skeptical weighing of the evidence, hypnotherapy was still proven effective. They showed conclusively that it was. In fact, their analysis of treatment designs concluded that expansion of the meta-analysis to include non-randomized trials for this data base would also produce reliable results. When all 133 studies deemed suitable in light of this consideration were re-analyzed, providing data for over 6,000 patients, the findings suggest an average improvement in 27% of untreated patients over the term of the studies compared with a 74% success rate among those receiving hypnotherapy. This is a high success rate given the fact that many of the studies measured included the treatment of addictions and medical conditions. The outcome rates for anxiety disorders alone, traditionally hypnotherapy’s strongest application, were higher still (though a precise figure is not cited).
In 2005, a meta-analysis by the Cochrane Collaboration found no evidence that hypnotherapy was more successful than other treatments or no treatment in achieving cessation of smoking for at least six months. In 2007 a meta-analysis from the Cochrane Collaboration found that the therapeutic effect of hypnotherapy was “superior to that of a waiting list control or usual medical management, for abdominal pain and composite primary IBS symptoms, in the short term in patients who fail standard medical therapy”, with no harmful side-effects. However the authors noted that the quality of data available was inadequate to draw any firm conclusions.