A young semi-eomatose male patient was investigated using 99mTc hexamethyl-propylene amine oxime (99mTc HMPAO) brain single photon emission computed tomography (SPECf) before and after administration of the gamma-aminobutyric acid (GABA) agonist zolpidem. It was observed that 15 minutes after application of the drug the patient awoke from his semi-eomatose condition and remained awake for the next 3 - 4 hours. When drug action subsided he returned to his semi-eomatose state. Brain SPECf before drug application showed large hypo-active areas in certain parts of the brain. Brain SPECf after drug application showed a generalised cortical activation relative to the cerebellum and a marked and amplified activation of the areas that were hypo-active before drug application.