Telomeres—the protective tips on the ends of each DNA strand—are a primary sign of aging; the longer the telomere, the younger the cell age. In one study, 55 people with weakening vision from age-related macular degeneration (AMD) took 3 mg of melatonin per day. After six months, 75 percent had stable eyesight and fewer AMD symptoms. In AMD, the retina deteriorates over time.
In a new theory, doctors said that the antioxidants in melatonin help retinal pigment cells repair oxidative damage and stimulate the cells to produce telomerase, a protein that helps maintain healthy telomere length.