Is melatonin circadian rhythm a physiological feature associated with healthy longevity? A study of long-living subjects and their progeny.

The study investigates the circadian rhythm (CR) of urinary 6-sulphatoxy-melatonin (aMT6s) in long-living (longevous) subjects and their progeny. The aim is to detect whether or not the melatonin CR is a physiological feature associated with healthy longevity. The aMT6s CR was investigated in 10 longevous subjects, 8 of their children and 9 of their grandchildren, all in good health. Control data were obtained respectively from 13 adult subjects and 9 young subjects, in good health, but characterized by a negative family history for longevity. All the subjects were born and living in the same city. The study was performed in the summer of 1996. The aMT6s CR was found to persist in longevous subjects, being characterized by a lower mesor and amplitude. The aMT6s CR was found not to show properties consistently different in children and grandchildren as compared respectively to their adult and young controls. Because of its preservation in longevous subjects, it can be argued that the melatonin CR is a physiological feature associated with healthy longevity. Because of the comparability of aMT6s CR in children and grandchildren, with respect to their controls without a positive family history of longevity, it can be argued that the melatonin CR is not a marker that can be used for an earlier identification of the candidates for longevity.