A group of drugs which depress the CENTRAL NERVOUS SYSTEM by inhibiting the transmission of impulses between neurons (see NEURON(E)). Thus they cause drowsiness or unconsciousness (depending on dose), reduce the cerebral metabolic rate for oxygen, and depress respiration. Their use as sedatives and hypnotics has largely been superseded by more modern drugs which are safer and more effective. Some members of this group of drugs – for instance, phenobarbitone – have selective anticonvulsant properties and are still sometimes used in the treatment of GRAND MAL convulsions and STATUS EPILEPTICUS (see EPILEPSY). The short-acting drugs thiopentone and methohexitone are widely used to induce general ANAESTHESIA. (See also DEPENDENCE.)