High hypnotizable people with PHA typically show impaired explicit memory, or difficulty consciously recalling events or material targeted by the suggestion, and a dissociation between implicit and explicit memory, so that even though they can’t recall the forgotten information it continues to influence their behavior, thoughts and actions. The forgetting is reversible—when the suggestion is cancelled, their memories come flooding back. These last two features—the dissociation and reversibility—confirm that PHA is not the result of poor encoding of the memories or of normal forgetting, because the memories return as soon as PHA is cancelled. Rather, PHA reflects a temporary inability to retrieve information that is safely stored in memory. That makes it a useful tool for research.
Most relaxation techniques require daily practice to be effective. A variety of formats for teaching relaxation and meditation exist, including classes as well as individual sessions. Relaxation can be taught in 1 session by conducting and audio taping a relaxation session. Using the audio tape, patients can then practice the techniques daily at home. Methods such as progressive muscle relaxation are easy to learn; yoga, tai chi, and meditation can take years to master completely.
In 2011, a Russian "evil hypnotist" was suspected of tricking customers in banks around Stavropol into giving away thousands of pounds worth of money. According to the local police, he would approach them and make them withdraw all of the money from their bank accounts, which they would then freely give to the man. A similar incident was reported in London in 2014, where a video seemingly showed a robber hypnotizing a shopkeeper before robbing him. The victim did nothing to stop the robber from looting his pockets and taking his cash, only calling out the thief when he was already getting away.
Hypnosis or deep relaxation can sometimes exacerbate psychological problems—for example, by retraumatizing those with post-traumatic disorders or by inducing “false memories” in psychologically susceptible individuals. Evidence, although inconclusive, has raised concerns that the dissociation necessary to participate in relaxation or hypnosis can lead to the manifestation of the symptoms of psychosis. Only appropriately trained and experienced practitioners should undertake hypnosis. Its use should be avoided in patients with borderline personality disorder, dissociative disorders, or with patients who have histories of profound abuse. Competent hypnotherapists are skilled in recognizing and referring patients with these conditions.
Although most practitioners receive their training in hypnotherapy or relaxation as a part of their academic training, the American Society of Clinical Hypnosis and the Society for Clinical and Experimental Hypnosis maintain training programs as well as a registry of practitioners (see previous box). Training in teaching relaxation techniques is provided through various routes from self-teaching and apprenticeships to a number of short courses. Many yoga centers also teach relaxation and offer courses to train yoga teachers.teachers.
Hypnotherapy has been studied for the treatment of irritable bowel syndrome. Hypnosis for IBS has received moderate support in the National Institute for Health and Clinical Excellence guidance published for UK health services. It has been used as an aid or alternative to chemical anesthesia, and it has been studied as a way to soothe skin ailments.
Modern hypnotherapy is widely accepted for the treatment of certain habit disorders, to control irrational fears, as well as in the treatment of conditions such as insomnia and addiction. Hypnosis has also been used to enhance recovery from non-psychological conditions such as after surgical procedures, in breast cancer care and even with gastro-intestinal problems, including IBS.