Until 30 years ago there were few clinical trials examining hypnosis for any type of medical or psychological problem. Scientific evidence for clinical hypnosis was limited to anecdotal and clinical reports. In recent decades, however, there has been a growing body of scientific research. Numerous controlled studies have found clinical hypnosis as effective or more effective than various treatments for pain including standard care, relaxation training, support group without hypnosis, attention control, autogenic training, biofeedback, and physical therapy.

In 1958 both the American Medical Association and the American Psychological Association recognized hypnotherapy as a valid medical procedure. Since 1995 the National Institute of Health (NIH) has recommended hypnotherapy as a treatment for chronic pain. Clinical hypnosis is one of the evidence-based complementary and integrative health approaches covered by the Veterans medical benefits package when deemed clinically necessary by their care team per VA directive.

This growing number of psychophysiological studies on hypnosis and pain has enhanced the scientific legitimacy of hypnosis, has identified several measurable physiological phenomena, and has put to rest the misconception that hypnosis is solely a placebo effect (David R. Patterson, 2013). Studies of laboratory pain reduction show sympathetic responses (e.g., heart rate and blood pressure), electrocortical activity at various sites, endogenous endorphin release, and regional blood flow. Clinical hypnosis demonstrates a series of physiological changes that can be monitored by brain activity.

A pilot study (Forester-Miller, H. 2017) on the integration of clinical hypnosis with patients in cancer care found significant changes in reported quality of life including improved emotional well-being (e.g., feeling less sad, feeling less nervous, experiencing less fear of dying, and being less worried that their condition will get worse), improved physical well-being (e.g., felt less ill, less bothered by the side effects of treatment, and less trouble meeting their family needs), improved functional well-being (e.g., more able to enjoy life, more able to sleep well, more able to enjoy the things they usually do for fun, and more content with the quality of their life). Additional studies have also found promising results including hypnosis patients reporting less pain intensity, pain unpleasantness, nausea, fatigue, discomfort, emotional upset, as well as requiring less anesthesia (Montgomery et al. 2002). Brief (4-5 sessions) self-hypnosis training for symptoms management resulted in decreases in pain intensity, fatigue, and sleep problems (Jensen et al. 2012). A 2014 review (Syrjala, K.LL. et al.) found strong evidence that hypnosis reduces multiple types of pain, with multiple cancer diagnoses, including diagnostic procedures, surgery, treatment-related procedures and treatment related pain.