Circadian Dysregulation and Melatonin Rhythm Suppression in the Context of Aging

Abstract

Fifty years ago, little was known of the role of the prevailing light: dark environment in terms of its impact on the circadian pathophysiology of organisms. In the intervening years the field of photoperiodic regulation of the master circadian oscillator, i.e., the suprachiasmatic nucleus (SCN), has advanced at a rapid pace. The importance of the regulatory actions of the light: dark cycle, and particularly of perturbed light: dark cycles, not only on the SCN but also on the circadian production of pineal melatonin as well as the cyclic metabolism of cells throughout the body are by no means trivial. When the regular cyclic information generated and dispensed by the SCN is dysregulated, the negative consequences in terms of cellular and organismal physiology can be dire to the extent that the rate of aging and the onset and progression of a variety of age-related diseases have now been at least provisionally linked to circadian disruption and/or melatonin suppression. While the findings are not definitive, there is certainly credible data to warrant the conclusion that regular circadian rhythms at multiple levels, including a stable day: night melatonin cycle, enhance life quality and potentially delay senescence and forestall diseases normally associated with advanced age. As a result, the prolonged health span may also predispose to a longer life span. In view of the critical role of an abnormal or unusual light environment in terms of perturbing essential circadian physiological events, serious consideration should be given to rational thought about the misuse of artificial light and the consequences thereof.