Table 2.

 Irritable bowel syndrome (IBS) symptom scores before and after two weeks of treatment

Parameter	Before melatonin treatment (absolute baseline score)*		After melatonin treatment (decrease in score)		p Value†
	Melatonin	Placebo	Melatonin	Placebo
Abdominal pain	4.05 (0.28)	3.85 (0.32)	2.35 (0.30)	0.70 (0.25)	<0.001
Abdominal distension	4.00 (0.36)	3.15 (0.38)	1.05 (0.38)	0.15 (0.29)	0.069
Frequency of defecation	3.25 (0.32)	3.15 (0.43)	1.85 (0.39)	0.85 (0.37)	0.070
Stool type	6.15 (0.60)	6.25 (0.54)	0.65 (0.60)	0.55 (0.37)	NS
Abnormal sensation of defecation	7.10 (1.02)	7.70 (0.95)	1.30 (0.80)	1.35 (0.65)	NS
Quality of life	5.80 (0.84)	5.45 (0.65)	1.25 (0.20)	0.95 (0.17)	NS
Total bowel symptom score‡	30.35 (1.84)	29.55 (1.93)	7.30 (1.37)	3.95 (1.25)	0.078

All data are geometric mean (SEM).

*No statistically significant differences between the melatonin and placebo groups for any of the absolute baseline scores.

†Comparisons between the melatonin and placebo groups after two weeks of treatment.

‡Total bowel symptom score >20.0 suggests the presence of significant bowel dysfunction.