In his later works, Braid reserved the term "hypnotism" for cases in which subjects entered a state of amnesia resembling sleep. For other cases, he spoke of a "mono-ideodynamic" principle to emphasise that the eye-fixation induction technique worked by narrowing the subject's attention to a single idea or train of thought ("monoideism"), which amplified the effect of the consequent "dominant idea" upon the subject's body by means of the ideo-dynamic principle.[57]
Advertisers have used this knowledge forever. They get our focus and then they pull us in with keywords and authoritative speech that enter the subconscious mind, bypassing our mental filters. Even as you read this, your mind is focused on the words you are reading and you are not fully aware of the world around you. So trance is a very natural state of mind and doesn't feel weird or different from what you often feel every day.
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.

This finding—that PHA temporarily disrupted some people’s ability to recall the past—echoes decades of hypnosis research. What is entirely new in Mendelsohn et al.’s study is their demonstration that PHA was associated with a specific pattern of brain activation. Consistent with what normally occurs in remembering, when people in the non-PHA group performed the recognition task and successfully remembered what happened in the movie, fMRI showed high levels of activity in areas responsible for visualizing scenes (the occipital lobes) and for analyzing verbally presented scenarios (the left temporal lobe). In stark contrast, when people in the PHA group performed the recognition task and failed to remember the content of the movie, fMRI showed little or no activity in these areas. Also, fMRI showed enhanced activity in another area (the prefrontal cortex) responsible for regulating activity in other brain areas.
Although there are different techniques, clinical hypnotherapy is generally performed in a calm, therapeutic environment. The therapist will guide you into a relaxed, focused state and ask you to think about experiences and situations in positive ways that can help you change the way you think and behave. Unlike some dramatic portrayals of hypnosis in movies, books, or on stage, you will not be unconscious, asleep, or in any way out of control of yourself. You will hear the therapist’s suggestions, but it is up to you to decide whether or not to act on them.