Various forms of hypnosis, trance, and altered states of consciousness have played roles across cultures throughout history. Hypnosis-like practices can be traced to ancient Egypt, Babylon, Greece, Persia, Britain, Scandinavia, America, Africa, India, and China. Wong Tai, a father of Chinese medicine, made an early written reference to hypnosis in 2600 BC. Hypnotic practices have played roles in religion and religious ceremonies. Mention is made in the Bible, Talmud, and Hindu Vedas, and trance-states are included in some Native American and African ceremonies.
The term hypnosis is derived from the Greek word hypnos, meaning sleep. The origin of modern Western hypnotherapy is often traced to the Austrian physician Franz Anton Mesmer (1734-1815). Mesmer believed that illness is caused by an imbalance of magnetic fluids in the body that can be corrected through "animal magnetism." He asserted that the hypnotist's own personal magnetism can be transferred to a patient. The term "mesmerize" is derived from Mesmer's name.
In the mid 20th Century, the British and American Medical Associations and the American Psychological Association endorsed hypnosis as a medical procedure. In 1995, the United States National Institutes of Health issued a consensus statement noting the scientific evidence in favor of the use of hypnosis for chronic pain, particularly pain associated with cancer.
The process of hypnotherapy can be divided into pre-suggestion, suggestion, and post-suggestion phases. The pre-suggestion component may include selective attentional focusing with distraction, imagery, and relaxation methods. An aim is to reach an altered state of consciousness in which the conscious mind is relaxed, the unconscious mind is more accessible, and the subject is susceptible to suggestion. In the suggestion phase, specific goals or impressions are presented, questions may be asked of the subject, or memories may be explored. The post-suggestion phase occurs after a return to a normal state of consciousness, and new behaviors based on hypnotic suggestions may be practiced. It has been suggested that there is a risk of false memories (confabulation) as a result of some types of hypnotherapy, although scientific research is limited in this area.
The degree of susceptibility to hypnosis and suggestion appears to vary between individuals. The therapeutic goals of hypnotherapy also vary, and may include the treatment of psychological or medical conditions or alteration of behaviors/habits. Subjects may seek hypnotherapy to gain control over behaviors or emotions. Self-hypnosis techniques may be used as an adjunct to sessions with a hypnotherapist.
There is wide variation in the training and credentials of hypnotherapists. Certification is granted by multiple organizations, with different requirements. In the United States, there is no universally accepted standard or licensing for hypnotherapists. Although many therapists are not licensed medical professionals, some doctors, dentists, and psychologists are trained in hypnotherapy and may use hypnosis in their practices. Books and audiotapes are available for training in self-hypnosis, although these have not been well evaluated scientifically. Group sessions may also be offered. The length of hypnosis sessions may vary from a single brief encounter to regularly scheduled longer appointments.
Abreaction therapy, altered states of consciousness, antenatal self-hypnosis, autogenic training, auto-hypnosis, aversion therapy, biofeedback, conditioning therapy, creative visualization, dream therapy, guided imagery, hypnoanalgesia, hypnobirthing, imagery, imagination training, meditation, mesmerism, pain relief therapy, post-hypnotic suggestion, regression therapy, relaxation, relaxation mental imagery (RMI), selective attention, self-hypnosis, shamanism, symptom relief therapy, trance, visualization.