[Melatonin: ulcer disease and seasons of the year].

Melatonin produces a great variety of effects in human organism and plays an essential role in normal function of the body. This explains growing interest of medical researchers to this substance. The paper provides the results of 3-year studies of seasonal rhythm of melatonin production in patients with duodenal ulcer. Acute disorders of circadian and seasonal melatonin production in summer and autumn were discovered in patients with duodenal ulcer. These findings suggest involvement of abnormal melatonin production in pathological mechanisms of autumn exacerbations of duodenal ulcer.