A recent study indicates that melatonin, a naturally occurring hormone commonly used to aid sleep, may be effective in treating uveitis, an inflammation of the middle layer of the eye which may result from a variety of causes, including eye injury, cancer, infection, and autoimmune diseases such as rheumatoid arthritis and multiple sclerosis. From the report:

Researchers lead by Dr. Ruth Rosenstein of The University of Buenos Aires and The National Research Council (CONICET) hypothesized that melatonin, which regulates sleep/wake cycles and reduces jet lag, may be able to prevent the ocular inflammation in uveitis. They found in an experimental model of uveitis that levels of two factors that contribute to inflammation, TNFα and NFκB, were reduced with melatonin treatment. Importantly, melatonin treatment also decreased the appearance of clinical symptoms of uveitis such as inflammation, blood vessel expansion and cataract, and protected the blood-ocular barrier integrity.

Taken together, the data from Sande et al suggest that "melatonin, which lacks adverse collateral effects even at high doses, could be a promising resource in the management of uveitis. Alone or combined with corticosteroid therapy, the anti-inflammatory effects of melatonin may benefit patients with chronic uveitis and decrease the rate and degree of corticosteroid-induced complications."

For further reading, the study was published in American Journal of Pathology, doi:10.2353/ajpath.2008.080518.