Genetically engineered animals (e.g., transgenics, gene knockouts, gene knockins) are being utilized with increasing frequency to investigate the mechanisms of action of alcohol and anesthetics. By creating and analyzing animals that harbor precise, preplanned changes in candidate genes, researchers are rapidly making progress toward uncovering how these drugs exert their effects on the central nervous system to bring about their behavioral effects. Since these sedative / hypnotic agents are likely to exert their effects by altering neurotransmission, the majority of investigations to date have focused on neurotransmitter receptors and modulators of neurotransmission such as kinases.