Final answer:
Alcohol, barbiturates, and GHB are all classified as sedative-hypnotics.
Step-by-step explanation:
The drugs that are classified as sedative-hypnotics include alcohol, barbiturates, and GHB (Gamma-Hydroxybutyrate). Barbiturates are CNS depressants that are similar to the depressant effects of alcohol. They are drugs derived from barbituric acid and have sedative and hypnotic effects. GHB is a central nervous system depressant that is commonly used as a recreational drug.