An interesting experiment on emotions was done with hypnosis on patients diagnosed with irritable bowel syndrome.
The researchers wanted to investigate how different emotions such as excitement, anger, and happiness would affect the muscle movement of the colon. 18 patients aged 20-48 years with irritable bowel syndrome took part in this hypnosis study.

The patients were hypnotized and were instructed to feel anger, excitement, or happiness. Colonic motility or movement as well as the respiration rate were used as a measurement.

Anger and excitement increased the colonic movement and respiration rates. Happiness further reduced colonic motility although not significantly from that observed during hypnosis alone. So here we have proof that emotions, positive or negative, do have an effect on the large intestine. (1)

Also, from our experience we know that there seems to be a close relationship between stress and bowel function. A recent study confirmed this relationship between daily stress and digestive symptoms on women with or without irritable bowel syndrome. The analyses found a significant and positive relationship between daily stress and daily symptoms such as bloating and diarrhea. Both groups, those with or without IBS, were affected. (2)

Fear and panic also have a direct influence on bowel function. A study compared patients who were diagnosed and seeking treatment for panic disorder and a control group of individuals without any panic disorder. Irritable bowel syndrome was diagnosed in 46.3% of the patients with panic disorder. In contrast, only 2.5% of the patient in the control group with no panic disorder had IBS. (3)

One study specifically looked at the effect of anger on the colon in irritable bowel syndrome. Patients with Irritable Bowel Syndrome were compared with normal controls.

Both groups were examined during rest and two anger stressors. The two anger situations consisted of 1) criticism of performance on an intelligence test and 2) a delay for help during a medical procedure.

At rest, patients with irritable bowel syndrome had more active colons than normal subjects. Anger significantly increased colon muscle activity in both groups compared with the resting state. However, patients with irritable bowel syndrome produced significantly higher colon muscle activity when angered. They also reported themselves to be more hostile and appeared angrier than normal controls after the study.(4)

Researchers are also looking into the relationship between sexual abuse and irritable bowel syndrome.

They took psychiatric and sexual trauma interviews of 28 patients with irritable bowel syndrome and 19 patients with inflammatory bowel disease. They then compared the frequency of sexual abuse in the two groups.

The results were revealing. Patients with irritable bowel syndrome had a significantly higher rate of severe sexual trauma (32% versus 0%) and severe childhood sexual abuse (11% versus 0%) as compared with patients with inflammatory bowel problems. (5)

References:

1. Physiological effects of emotion: assessment via hypnosis. Whorwell PJ, Houghton LA, Taylor EE, Maxton DG. Lancet 1992 Jul 11;340(8811):69-72

2. The relationship between daily life stress and gastrointestinal symptoms in women with irritable bowel syndrome. Levy RL, Cain KC, Jarrett M, Heitkemper MM. J Behav Med 1997 Apr;20(2):177-193

3. The relationship of irritable bowel syndrome (IBS) and panic disorder. Kaplan DS, Masand PS, Gupta S. Ann Clin Psychiatry 1996 Jun;8(2):81-88

4. Effect of anger on colon motor and myoelectric activity in irritable bowel syndrome. Welgan P, Meshkinpour H, Beeler M. Gastroenterology 1988 May;94(5 Pt 1):1150-1156

5. Histories of sexual victimization in patients with irritable bowel syndrome or inflammatory bowel disease. Walker EA, Katon WJ, Roy-Byrne PP, Jemelka RP, Russo J. Am J Psychiatry 1993 Oct;150(10):1502-1506

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