When people with irritable bowel syndrome (IBS) were asked to relate their mood to a color, those choosing a positive color were nine times more likely to respond to hypnotherapy than those who chose a negative color or no color at all. Researchers writing in the open access journal BMC Complementary and Alternative Medicine suggest that these findings could be used to predict responders to treatment.

Peter Whorwell worked with a team of researchers from the University of Manchester, UK, to carry out the study using a color chart called the 'Manchester Color Wheel' which allows patients to choose colors that have previously been defined as positive, neutral or negative. He said, "Our unit has been providing hypnotherapy for the treatment of IBS for over twenty years with approximately two thirds of patients responding to treatment. Unfortunately, patients may require as many as twelve one hour sessions of therapy to secure a response and therefore this results in the treatment being relatively expensive to provide. Consequently it would be very useful to be able to predict responders".

Speaking about the results Whorwell said, "Being able to describe mood in terms of a positive color is a sign of an active imagination, which is an important component of hypnotic ability". The hypnotherapy provided in Professor Whorwell's Unit is called gut-focused hypnotherapy. The technique aims to give a patient control over their gut and they have shown that following a course of treatment actual changes in gastrointestinal function can be demonstrated.