Which category of sedative-hypnotics targets melatonin receptors?

The category of sedative-hypnotics that targets melatonin receptors is comprised of melatonin agonists. These medications mimic the natural hormone melatonin, which plays a crucial role in regulating sleep-wake cycles. By binding to melatonin receptors in the brain, these agents promote sleep and help manage circadian rhythm disorders. This specific action on melatonin receptors distinguishes them from other sedative-hypnotics, which function through different mechanisms.

For instance, barbiturates primarily enhance the effect of gamma-aminobutyric acid (GABA) at the GABA-A receptor, leading to sedation and hypnosis. Antihistamines work by blocking histamine receptors, which may induce sedation as a side effect, but do not specifically target melatonin receptors. Benzodiazepines also enhance GABA-A receptor activity, providing anxiolytic and sedative effects without acting on melatonin receptors. Thus, melatonin agonists are unique in their targeted action, making them the correct answer.