Final answer:
Depressants are drugs that suppress central nervous system activity by increasing the effects of the neurotransmitter GABA. They have a quieting effect on the brain and can be used to treat anxiety and insomnia.
Step-by-step explanation:
Depressants are drugs that tend to suppress central nervous system activity. They work by increasing the effects of the neurotransmitter GABA in the brain. GABA has an inhibitory effect on cells, meaning it has a quieting effect on the brain. GABA agonists, such as barbiturates and benzodiazepines, promote the activity of GABA receptors and can be used to treat anxiety and insomnia.