Abstract
This paper reviews the possible generation mechanism of the circadian time signal in the suprachiasmatic nucleus in mammals, based on our findings that continuous infusion of insulin into rat brain caused complete losses of various circadian rhythms. This also describes the role of the suprachiasmatic nucleus as the central site of regulation of energy supply to the brain. From these two aspects, dependency of our lives on the circadian clock and contribution of such researches to medical biology are discussed.
