Kurt Kräuchi University of Basel, CH Title Thermophysiological aspects of the three-process-model of sleepiness regulation Abstract My lecture will provide an overview reconsidering the three-process -model of sleepiness regulation (homeostatic, circadian and sleep inertia) from a thermophysiological point of view. Our studies conducted over the last decade indicate that the homeostatic aspect of sleepiness regulation (build-up of sleepiness during wake and decay of sleepiness during sleep) is not related to the thermoregulatory system, but the circadian aspect and sleep inertia is. Distal skin temperature of hands and feet seem to be the crucial variable for the connection between thermophysiology, sleepiness and sleep. Increased distal skin temperature before nocturnal sleep is a good predictor for short sleep onset latency. The disappearance of sleep inertia after sleep shows a very similar time course to distal vasoconstriction. Furthermore, relaxation-induced sleepiness (e.g. after lying down, at lights off, with thermal biofeedback training) also induces an increase in distal skin temperatures. The reverse occurs at lights on or standing up: sleep inertia can be explained thermophysiologically as the reverse relaxation process by a decrease in distal skin temperatures. Our results reinterprets the so-called sleep-evoked reduction of core body temperature as a consequence of relaxation-induced vasodilatation after light off. Sleep per se has no further thermoregulatory effect.   Education 1969-1972 Chemical Laboratory Assistant 1972-1975 Chemical Engineer, FH –Basel 1993-1994 Nachdiplomkurs in angewandter Statistik der ETH Zürich   Present Position Senior Research Scientist Psychiatric University Clinic,Centre for Chronobiology, CH-4025 Basel   PI -SNF-Project „Thermophysiological approaches to the clinical problem of difficulties initiating sleep“ 2004-2007 (3 years)   Publications Kräuchi, K., Cajochen, C. & Wirz-Justice, A (2004). Waking up properly: is there a role of thermoregulation in sleep inertia? J. Sleep Res. 13:121-127. Kräuchi K, Cajochen C, Werth E, Wirz-Justice A. Functional link between distal vasodilation and sleep-onset latency? Am J Physiol Regul Integr Comp Physiol. 2000 Mar;278(3):R741-8. Kräuchi K, Cajochen C, Werth E, Wirz-Justice A. Warm feet promote the rapid onset of sleep. Nature. 1999 Sep 2;401(6748):36-7. Kräuchi K, Cajochen C, Wirz-Justice A. A relationship between heat loss and sleepiness: effects of postural change and melatonin administration. J Appl Physiol. 1997 Jul;83(1):134-9. Kräuchi K, Wirz-Justice A. Circadian rhythm of heat production, heart rate, and skin and core temperature under unmasking conditions in men. Am J Physiol. 1994 Sep;267(3 Pt 2):R819-29.