How does it work? Hypnosis is now a well-recognised scientific phenomenon, but there is still no accepted definition of what it constitutes. Some scientists speculate that it prompts the brain to release chemicals called enkephalins and endorphins, natural mood-altering substances that can change the way people perceive pain and other physical symptoms. A more popular view is that hypnosis involves the left side of the brain (the conscious mind) switching off and the right side of the brain (the unconscious mind) being allowed to run free. The Hemisphere of Brain The right side of the brain, associated with the subconscious mind, is concerned with fantasies and imagery. This takes over during hypnosis. The left side of the brain, associated with the conscious mind, is involved in logical reasoning and analysis. It switches off during hypnosis. According to Professor John Gruzelier, a psychologist at Charring Cross Medical School, London, the way to induce the hypnotic state is to provoke the left side of the brain to switch off, allowing the right side of the brain to take over. This can be done by making the brain focus on something monotonous such as a droning voice or a watch swinging on a chain. Once the left side realises there is nothing worth attending to, it hands over to the right side.