Therefore, if melatonin exerts an inhibitory [20,21] effect on insulin secretion, and because many studies suggest that amino acids and insulin play major roles in promoting postprandial protein anabolism [22,23], the hypothesis arises that the intake of melatonin could have a detrimental effect on protein metabolism through the inhibition of insulin secretion, particularly so in sarcopenia, which has repeatedly been shown to be associated with muscle tissue resistance to the anabolic effects of insulin [24]. Here, INS is linked to sarcopenia.