Background and aims: Melatonin, a sleep promoting agent, is involved in the regulation of gastrointestinal motility and sensation. We aimed to determine if melatonin was effective in improving bowel symptoms and sleep disturbances in irritable bowel syndrome (IBS) patients with sleep disturbance. Methods: Forty IBS patients (aged 20–64 years; 24 female) with sleep disturbances were randomly assigned to receive either melatonin 3 mg (n = 20) or matching placebo (n = 20) at bedtime for two weeks. Immediately before and after the treatment, subjects completed bowel, sleep, and psychological questionnaires, and underwent rectal manometry and overnight polysomnography. Results: Compared with placebo, melatonin taken for two weeks significantly decreased mean abdominal pain score (2.35 v 0.70; p<0.001) and increased mean rectal pain threshold (8.9 v −1.2 mm Hg; p<0.01). Bloating, stool type, stool frequency, and anxiety and depression scores did not significantly differ after treatment in both groups. Data from sleep questionnaires and polysomnography showed that the two week course of melatonin did not influence sleep parameters, including total sleep time, sleep latency, sleep efficiency, sleep onset latency, arousals, duration of stages 1–4, rapid eye movement (REM) sleep, and REM onset latency. Conclusions: Administration of melatonin 3 mg at bedtime for two weeks significantly attenuated abdominal pain and reduced rectal pain sensitivity without improvements in sleep disturbance or psychological distress. The findings suggest that the beneficial effects of melatonin on abdominal pain in IBS patients with sleep disturbances are independent of its action on sleep disturbances or psychological profiles.

Objective: To investigate the incidence of gastric cancer (GC) attributed to gastric intestinal metaplasia (IM), and validate the Operative Link on Gastric Intestinal Metaplasia (OLGIM) for targeted endoscopic surveillance in regions with low-intermediate incidence of GC. Methods: A prospective, longitudinal and multicentre study was carried out in Singapore. The study participants comprised 2980 patients undergoing screening gastroscopy with standardised gastric mucosal sampling, from January 2004 and December 2010, with scheduled surveillance endoscopies at year 3 and 5. Participants were also matched against the National Registry of Diseases Office for missed diagnoses of early gastric neoplasia (EGN). Results: There were 21 participants diagnosed with EGN. IM was a significant risk factor for EGN (adjusted-HR 5.36; 95% CI 1.51 to 19.0; p<0.01). The age-adjusted EGN incidence rates for patients with and without IM were 133.9 and 12.5 per 100 000 person-years. Participants with OLGIM stages III–IV were at greatest risk (adjusted-HR 20.7; 95% CI 5.04 to 85.6; p<0.01). More than half of the EGNs (n=4/7) attributed to baseline OLGIM III–IV developed within 2 years (range: 12.7–44.8 months). Serum trefoil factor 3 distinguishes (Area Under the Receiver Operating Characteristics 0.749) patients with OLGIM III–IV if they are negative for H. pylori. Participants with OLGIM II were also at significant risk of EGN (adjusted-HR 7.34; 95% CI 1.60 to 33.7; p=0.02). A significant smoking history further increases the risk of EGN among patients with OLGIM stages II–IV. Conclusions: We suggest a risk-stratified approach and recommend that high-risk patients (OLGIM III–IV) have endoscopic surveillance in 2 years, intermediate-risk patients (OLGIM II) in 5 years.

Irritable bowel syndrome (IBS) is a common disorder characterized by recurrent abdominal pain or discomfort, in combination with disturbed bowel habits in the absence of identifiable organic cause. Melatonin (N-acetyl-5-methoxytryptamine) is a hormone produced by the pineal gland and also large number by enterochromaffin cells of the digestive mucosa. Melatonin plays an important part in gastrointestinal physiology which includes regulation of gastrointestinal motility, local anti-inflammatory reaction as well as moderation of visceral sensation. Melatonin is commonly given orally. It is categorized by the United States Food and Drug Administration as a dietary supplement. Melatonin treatment has an extremely wide margin of safety though it may cause minor adverse effects, such as headache, rash and nightmares. Melatonin was touted as a potential effective candidate for IBS treatment. Putative role of melatonin in IBS treatment include analgesic effects, regulator of gastrointestinal motility and sensation to sleep promoter. Placebo-controlled studies in melatonin suffered from heterogeneity in methodology. Most studies utilized 3 mg at bedtime as the standard dose of trial. However, all studies had consistently showed improvement in abdominal pain, some showed improvement in quality of life of IBS patients. Melatonin is a relatively safe drug that possesses potential in treating IBS. Future studies should focus on melatonin effect on gut mobility as well as its central nervous system effect to elucidate its role in IBS patients.