Corticotropin-releasing hormone (CRH) mediates responses to a variety of stressors. We subjected rats to a one hour period of an acute stressor, physical restraint, and determined the impact on subsequent sleep-wake behavior. Restraint at the beginning of the light period, but not the dark period, increased waking and reduced rapid eye movements sleep (REMS) without dramatically altering slow wave sleep (SWS). Electroencephalogram (EEG) slow wave activity during SWS and brain temperature were increased by this manipulation. Central administration of the CRH receptor antagonist astressin blocked the increase in waking after physical restraint, but not during the period of restraint itself. Blockade of CRH receptors with astressin attenuated the restraint-induced elevation of brain temperature, but not the increase of EEG slow wave activity during subsequent SWS. Although corticosterone increased after restraint in naïve animals, it was not altered by this manipulation in rats well-habituated to handling and injection procedures. These results suggest that under these conditions central CRH, but not the HPA axis is involved in the alterations in sleep-wake behavior and in the modulation of brain temperature of rats exposed to this stressor.