Thermogenesis and thermolysis during sleeping and waking in the rat.

Thermogenesis (VO2), sensible heat loss and subcutaneous back temperature were recorded simultaneously during sleeping and waking in both intact and depilated rats at Ra ranging from 21--28 degrees C. VO2 increased during wakefulness (W), decreased and plateaued during slow wave sleep (SWS) and then decreased 10% with each paradoxical sleep (PS) phase. Sensible heat loss, which represented about 90% of the heat production, increased and plateaued during SWS, decreased in W and generally rose abruptly (+40%) during PS. After removal of the fur the mean levels of VO2 and sensible heat loss were increased by 20--50% and returned to normal values within two weeks, although their variations related to stages of sleep were unchanged. These results concerning thermogenesis and thermolysis are in agreement with the variations of body temperature (brain excluded) during sleeping and waking.