The role of thermoregulation in the soporific effects of melatonin: A new perspective

Abstract

Melatonin was first purified nearly fifty years ago and has since been identified as a sleep promoting, thermoregulatory and circadian agent in humans. In this chapter we examine the shifting perspective on the endogenous functions of melatonin, from evidence examining its exogenous effects on central circadian physiology to its action on sleep via peripheral thermoregulation. We discuss the possibility that a function of melatonin is to initiate peripheral vasodilatation which, in turn, may act as a physiological trigger for sleep. From this exploration, we conclude that melatonin’s capacity to both promote distal peripheral heat loss and, hence, sleep, alone or in combination, act to reinforce circadian adaptation.