What is the main characteristic of CNS depressants?

CNS depressants are primarily characterized by their ability to reduce brain activity. This class of medications works by enhancing the effects of certain neurotransmitters, specifically gamma-aminobutyric acid (GABA), which helps to calm or sedate the central nervous system. As a result, these substances create a sedative effect, leading to decreased alertness, slower reaction times, and an overall calming influence on the mind and body.

This reduction in brain activity is particularly beneficial for treating conditions such as anxiety, insomnia, and some seizure disorders. By effectively slowing down the neural processes, CNS depressants can help individuals manage symptoms that stem from an overactive nervous system. The other options presented do not accurately reflect the primary function of CNS depressants; they either suggest an increase in brain activity or promote hyperactivity, which contradicts the sedative effects associated with these substances.