During the last 20 years, numerous clinical trials have examined the therapeutic usefulness of
melatonin in different fields of medicine. The objective of this article is to review, in depth, the science regarding clinical trials performed to date. The efficacy of
melatonin has been assessed as a treatment of ocular
diseases, blood diseases, gastrointestinal tract diseases,
cardiovascular diseases, diabetes,
rheumatoid arthritis,
fibromyalgia,
chronic fatigue syndrome,
infectious diseases, neurological diseases, sleep disturbances, aging and depression.
Melatonin has been also used as a complementary treatment in anaesthesia,
hemodialysis, in vitro fertilization and neonatal care. The conclusion of the current review is that the use of
melatonin as an adjuvant
therapy seems to be well funded for
macular degeneration,
glaucoma, protection of the gastric mucosa,
irritable bowel syndrome, arterial
hypertension, diabetes, side effects of
chemotherapy and radiation in
cancer patients or
hemodialysis in patients with
renal insufficiency and, especially, for
sleep disorders of circadian etiology (
jet lag,
delayed sleep phase syndrome, sleep deterioration associated with aging, etc.) as well as in those related with neurological degenerative diseases (Alzheimer, etc.,) or
Smith-Magenis syndrome. The utility of
melatonin in
anesthetic procedures has been also confirmed. More clinical studies are required to clarify whether, as the preliminary data suggest,
melatonin is useful for treatment of
fibromyalgia,
chronic fatigue syndrome,
infectious diseases,
neoplasias or neonatal care. Preliminary data regarding the utility of
melatonin in the treatment of
ulcerative colitis,
Crohn's disease,
rheumatoid arthritis are either ambiguous or negative. Although in a few cases
melatonin seems to aggravate some conditions, the vast majority of studies document the very low toxicity of
melatonin over a wide range of doses.