A perspective on the proposed association of melatonin and aging

Melatonin, the chief secretory product of the pineal gland, has been proposed to have some functional association with aging. Certainly, melatonin production in vertebrates, including humans, wanes with increasing age. This age-related drop in melatonin has been inferred to be consequential in terms of accelerating some aspects of aging, although the experimental evidence for this is not compelling at this point. There are several functional aspects of melatonin that make it of interest to gerontologists. Thus, the cyclic production of melatonin is reflective of the biological clock, and circadian disturbances in general are a feature of aging. These alterations may impact the rate of aging. Also, melatonin is an antioxidant and, as such, it reduces free radical damage. A primary theory of aging is accumulated oxidative damage, and any molecule, such as melatonin, that retards the accumulation of that molecular damage may forestall some aging processes. The experimental data are incomplete, however, and the specific association of the diminished melatonin cycle with aging or age-related diseases remains suggestive but unproven.