Final answer:
Alcohol is a legal depressant that has a quieting effect on the brain. It is commonly used and can induce sleepiness and reduce anxious feelings.
Step-by-step explanation:
Alcohol (ethanol) is a legal depressant. Depressants, such as alcohol, have a quieting effect on the brain by suppressing central nervous system activity. They can induce sleepiness and reduce anxious feelings. Other examples of depressants include barbiturates and benzodiazepines, which are prescribed to treat anxiety and insomnia.