Which statement best describes sedative-hypnotics?

• A. They are exclusively benzodiazepines.
• B. They never cause daytime sleepiness.
• C. Sedative-hypnotics at high doses calm the CNS and cause sleep.
• D. They are rarely used clinically.

Answer: (C)

Sedative-hypnotics are drugs that depress the central nervous system to calm or induce sleep. The key idea is dose-related: at lower doses they mainly sedate, but at higher doses the brain is depressed enough to produce hypnosis, i.e., sleep. That makes the statement about calming the CNS and causing sleep at high doses the best description of what these drugs do. It’s not limited to benzodiazepines—barbiturates and other non-benzodiazepine hypnotics are also in this category, so claiming exclusivity to benzodiazepines is incorrect. They can cause daytime sleepiness or residual sedation in some people, and they’re commonly used clinically for sleep disorders, anxiety, and preoperative sedation, so saying they are rarely used is false.