Final answer:
Sedative-hypnotic agents predominantly bind to GABA receptors in the brain, enhancing the inhibitory effects and producing a depressive effect on the central nervous system, aiding in the treatment of anxiety and insomnia.
Step-by-step explanation:
Sedative-hypnotic agents primarily bind to GABA (gamma-aminobutyric acid) receptors in the brain. GABA is the main inhibitory neurotransmitter in the central nervous system (CNS), and drugs like barbiturates and benzodiazepines serve as agonists at the GABA neurotransmitter system. These drugs enhance the inhibitory effects of GABA, leading to a depressive effect on the central nervous system, which is beneficial for treating conditions such as anxiety and insomnia. The activation of GABA receptors by these sedative-hypnotic agents opens the chloride channel, allowing negatively-charged chloride ions into the neuron, making it less likely to fire and therefore exerting a quieting effect on the brain.