The role of consciousness in stress-induced analgesia.

Male rats received unavoidable footshock administered while either awake or under Halothane anaesthesia. Tail-flick threshold was measured subsequently in awake rats. An elevation in pain threshold indicative of stress-induced analgesia (SIA) appeared in rats shocked while awake, but not in those shocked while anaesthetized. The findings suggest that conscious processes are necessary for the occurrence of SIA.