In stupor there is a reduction of alertness, a semi-consciousness from which the patient can be partially aroused. Stupor may represent a mild degree of coma or shock. It may progress to more severe coma or shock or unconsciousness. It may occur, then, in a person under the influence of drugs or seized by an attack of epilepsy. In cases of mental illness, the term stupor describes a condition of reduced responsiveness, as in depression or dementia.