The practice of many relaxation techniques is poorly regulated, and standards of practice and training are variable. This situation is unsatisfactory, but given that many relaxation techniques are relatively benign, the problem with this variation in standards is more in ensuring effective treatment and good professional conduct than in avoiding adverse effects. By selecting a license mental health professional (psychologist or social worker), patients are more likely to receive treatment from individuals who are well trained in the appropriate use of behavioral techniques.
He also believed that hypnosis was a "partial sleep", meaning that a generalised inhibition of cortical functioning could be encouraged to spread throughout regions of the brain. He observed that the various degrees of hypnosis did not significantly differ physiologically from the waking state and hypnosis depended on insignificant changes of environmental stimuli. Pavlov also suggested that lower-brain-stem mechanisms were involved in hypnotic conditioning.[166][167]
Abnormal results can occur in instances where amateurs, who know the fundamentals of hypnosis, entice friends to become their experimental subjects. Their lack of full understanding can lead to immediate consequences, which can linger for some time after the event. If, for example, the amateur plants the suggestion that the subject is being bitten by mosquitoes, the subject would naturally scratch where the bites were perceived. When awakened from the trance, if the amateur forgets to remove the suggestion, the subject will continue the behavior. Left unchecked, the behavior could land the subject in a physician's office in an attempt to stop the itching and scratching cycle. If the physician is astute enough to question the genesis of the behavior and hypnosis is used to remove the suggestion, the subject may experience long-term negative emotional distress and anger upon understanding exactly what happened. The lack of full understanding, complete training, and supervised experience on the part of the amateur places the subject at risk.
Poor regulation of hypnosis and deeper relaxation techniques is more serious. Although several professional organizations exist, these groups do not regulate or certify practitioners in hypnotherapy or relaxation. Hypnotherapists with a conventional health care background (such as psychologists, physicians, dentists, and nurses) are regulated by their professional regulatory bodies. Psychotherapists who use hypnotherapy as an adjunctive treatment modality require appropriate training. Individuals who have received a master's degree in counseling or social work or a doctorate in clinical or counseling psychology will be likely to have received appropriate training and supervision.
The main theorist who pioneered the influential role-taking theory of hypnotism was Theodore Sarbin. Sarbin argued that hypnotic responses were motivated attempts to fulfill the socially constructed roles of hypnotic subjects. This has led to the misconception that hypnotic subjects are simply "faking". However, Sarbin emphasised the difference between faking, in which there is little subjective identification with the role in question, and role-taking, in which the subject not only acts externally in accord with the role but also subjectively identifies with it to some degree, acting, thinking, and feeling "as if" they are hypnotised. Sarbin drew analogies between role-taking in hypnosis and role-taking in other areas such as method acting, mental illness, and shamanic possession, etc. This interpretation of hypnosis is particularly relevant to understanding stage hypnosis, in which there is clearly strong peer pressure to comply with a socially constructed role by performing accordingly on a theatrical stage.
We also wonder how the suppression mechanism in PHA relates to the vast array of forgetting in the laboratory and in the world? Whereas some forgetting is seen as strategic, effortful and conscious (say, suppression), other forgetting is seen as automatic, effortless and unconscious (say, repression). Having mapped the common features of PHA and functional amnesia, we now need to explore and compare in greater detail their common processes (such as strategy use, motivation, level of awareness).
Hypnosis has been used as a supplemental approach to cognitive behavioral therapy since as early as 1949. Hypnosis was defined in relation to classical conditioning; where the words of the therapist were the stimuli and the hypnosis would be the conditioned response. Some traditional cognitive behavioral therapy methods were based in classical conditioning. It would include inducing a relaxed state and introducing a feared stimuli. One way of inducing the relaxed state was through hypnosis.[77]

The term "hypnosis" comes from the ancient Greek word ὕπνος hypnos, "sleep", and the suffix -ωσις -osis, or from ὑπνόω hypnoō, "put to sleep" (stem of aorist hypnōs-) and the suffix -is.[9][10] The words "hypnosis" and "hypnotism" both derive from the term "neuro-hypnotism" (nervous sleep), all of which were coined by Étienne Félix d'Henin de Cuvillers in 1820. These words were popularized in English by the Scottish surgeon James Braid (to whom they are sometimes wrongly attributed) around 1841. Braid based his practice on that developed by Franz Mesmer and his followers (which was called "Mesmerism" or "animal magnetism"), but differed in his theory as to how the procedure worked.

Milton Erickson (1901–1980), the founding president of the American Society for Clinical Hypnosis and a fellow of the American Psychiatric Association, the American Psychological Association, and the American Psychopathological Association, was one of the most influential post-war hypnotherapists. He wrote several books and journal articles on the subject. During the 1960s, Erickson popularized a new branch of hypnotherapy, known as Ericksonian therapy, characterised primarily by indirect suggestion, "metaphor" (actually analogies), confusion techniques, and double binds in place of formal hypnotic inductions. However, the difference between Erickson's methods and traditional hypnotism led contemporaries such as André Weitzenhoffer to question whether he was practising "hypnosis" at all, and his approach remains in question.

Some therapists use hypnotherapy to recover repressed memories they believe are linked to the person’s mental disorder. However, it also poses a risk of creating false memories—usually as a result of unintended suggestions by the therapist. For this reason, using hypnotherapy for certain mental disorders, such as dissociative disorders, remains controversial.

Since hypnotherapy is an adjunct form of therapy, used along with other forms of psychological or medical treatment, there are many applications. Hypnotherapy can be used to treat anxiety, phobias, substance abuse including tobacco, sexual dysfunction, undesirable spontaneous behaviors, and bad habits. It can be used to help improve sleep, learning disorders, communication, and relationship issues. Hypnotherapy can aid in pain management and help resolve medical conditions such as digestive disorders, skin issues, and gastrointestinal side effects of pregnancy and chemotherapy. It can also be used by dentists to help patients control their fears or to treat teeth grinding and other oral conditions.