He discovered that before the sessions, women were most concerned with quality of life issues such as diet and energy and that men had the highest levels of anxiety and depression and worried about their physical role.
The 20 men and 55 women who took part in the study reported that hypnotherapy brought about significant improvements in the physical and emotional symptoms related to IBS.
These included a 30 per cent improvement in their emotional quality of life and a 25 per cent improvement in energy levels.
Mental health improved by 21 per cent, sleep by 18 per cent, physical health by 16 per cent and diet by 14 per cent.
The participants also reported that their social role had improved by 20 per cent and their physical role by 18 per cent.
Average anxiety levels fell by 12 per cent and depression fell by four per cent. Men showed higher levels of both problems before the hypnotherapy sessions, but also reported greater improvements than women.
The people taking part in the study also reported a five per cent reduction in abdominal pain and a four per cent reduction in abdominal bloating.
"It is estimated that between 10 to 15 per cent of adults may suffer from IBS and that the physical, emotional, social and economic consequences of the illness can be considerable" says Dr Smith, from the University's School of Health (Nursing Studies).
"Physical symptoms include altered bowel habits, abdominal pain and bloating, together with other non-intestinal problems such as lethargy, problems sleeping and indigestion. Anxiety and psychosocial problems are also common and these can have a detrimental impact on quality of life."
The 75 study participants underwent hypnotherapy sessions that focussed on creating images of their gut symptoms using visualisation techniques in conjunction with relaxation methods.
Self-hypnosis was taught at an early stage and patients were given audio tapes, that reinforced the effects of the hypnotherapy, to use at home.
They also completed detailed questionnaires before and after treatment and kept diary cards during the study
"The patients involved in this study were typical of people seen routinely in gastroenterology clinics, where up to 50 per cent of the referrals are for IBS" says Dr Smith.
"There's no universal agreement about what causes IBS and traditional treatment is often disappointing. This study shows that hypnotherapy can effectively reduce symptoms and improve quality of life and underlines the valuable role that complementary therapies can play in modern healthcare."