“That study changed the whole landscape,” said Dave Patterson, a psychologist at the University of Washington in Seattle, who has been using hypnosis since the 1980s to help burn victims withstand the intense pain that comes with the necessary but excruciating bandage removal and wound cleaning. Since the ’90s, other well-designed, controlled studies have been published showing similar changes in brain activity. In another slightly trippy example, researchers suggested to people in a hypnotic state that the vibrant primary colors found in paintings by Piet Mondrian were actually shades of gray. “Brain-scan results of these participants showed altered activity in fusiform regions involved in color processing,” notes psychologist Christian Jarrett.
In 1974, Theodore X. Barber and his colleagues published a review of the research which argued, following the earlier social psychology of Theodore R. Sarbin, that hypnotism was better understood not as a "special state" but as the result of normal psychological variables, such as active imagination, expectation, appropriate attitudes, and motivation.[16] Barber introduced the term "cognitive-behavioral" to describe the nonstate theory of hypnotism, and discussed its application to behavior therapy.

Modern hypnotherapy is widely accepted for the treatment of certain habit disorders, to control irrational fears,[35][36] as well as in the treatment of conditions such as insomnia[37] and addiction.[38] Hypnosis has also been used to enhance recovery from non-psychological conditions such as after surgical procedures,[39] in breast cancer care[40] and even with gastro-intestinal problems,[41] including IBS.[42][43]
You are getting very sleepy.... While hypnosis is often associated with sideshow performances, it's not a magical act. Rather, it’s a technique for putting someone into a state of heightened concentration where they are more suggestible. Therapists use hypnosis (also referred to as hypnotherapy or hypnotic suggestion) to help patients break bad habits, such as smoking, or achieve some other positive change, like losing weight. They accomplish this with the help of mental imagery and soothing verbal repetition that eases the patient into a trance-like state; once relaxed, patients’ minds are more open to transformative messages. Hypnosis can also help people cope with negative emotional states, like stress and anxiety, as well as pain, fatigue, insomnia, mood disorders, and more. In rare cases where patients are resistant to hypnoses, alternative therapies may be used.  
State theorists interpret the effects of hypnotism as due primarily to a specific, abnormal, and uniform psychological or physiological state of some description, often referred to as "hypnotic trance" or an "altered state of consciousness". Nonstate theorists rejected the idea of hypnotic trance and interpret the effects of hypnotism as due to a combination of multiple task-specific factors derived from normal cognitive, behavioural, and social psychology, such as social role-perception and favorable motivation (Sarbin), active imagination and positive cognitive set (Barber), response expectancy (Kirsch), and the active use of task-specific subjective strategies (Spanos). The personality psychologist Robert White is often cited as providing one of the first nonstate definitions of hypnosis in a 1941 article:
Hypnotherapy can have negative outcomes. When used as entertainment, people have been hypnotized to say or do things that would normally embarrass them. There have been instances where people already dangerously close to psychological breakdown have been pushed into an emotional crisis during what was supposed to be a harmless demonstration of hypnosis. A statement from the World Hypnosis Organization (WHO) warns against performing hypnosis on patients suffering from psychosis, organic psychiatric conditions, or antisocial personality disorders. Because there are no standard licensing requirements, in the wrong hands, there is a risk that the hypnotist will have difficulty in controlling or ending a hypnotic state that has been induced in the patient.
In conventional hypnosis, you approach the suggestions of the hypnotist, or your own ideas, as if they were reality. If the hypnotist suggests that your tongue has swollen up to twice its size, you'll feel a sensation in your mouth and you may have trouble talking. If the hypnotist suggests that you are drinking a chocolate milkshake, you'll taste the milkshake and feel it cooling your mouth and throat. If the hypnotist suggests that you are afraid, you may feel panicky or start to sweat. But the entire time, you are aware that it's all imaginary. Essentially, you're "playing pretend" on an intense level, as kids do.

It is used for a wide variety of applications, and studies into its efficacy are often of poor quality[2] which makes it difficult to determine efficacy. Several recent meta-analyses and systematic reviews of the literature on various conditions have concluded that the efficacy of hypnotherapy is "not verified",[3] that there is no evidence[4][5] or insufficient evidence[6][7] for efficacy.