What is the collective term for psychoactive medications that suppress central nervous system activity?

The collective term for psychoactive medications that suppress central nervous system activity is indeed depressants. Depressants are substances that can reduce the levels of arousal and stimulation in the brain, leading to effects such as sedation, relaxation, and reduced anxiety. Common examples include alcohol, benzodiazepines, and barbiturates. These drugs work by enhancing the effects of neurotransmitters like gamma-aminobutyric acid (GABA), which is responsible for inhibitory processes in the brain.

In contrast, stimulants, such as caffeine and amphetamines, increase central nervous system activity and overall alertness. Hallucinogens alter perception and can create visual or auditory hallucinations without necessarily suppressing brain activity. Opioids primarily act on the body's pain relief system but also can depress central nervous system activity, though they are not classified under the broad category of depressants in the same way traditional depressants are. Thus, the correct answer is based on the specific classification of substances that primarily serve to suppress CNS activity, which is characteristic of depressants.