Depressants are used to do what?

Depressants are substances that work by slowing down the central nervous system and diminishing body functions or nerve activity. This effect leads to a calming or sedative impact, making them useful in medical situations for anxiety relief or sleep induction. By inhibiting brain activity, depressants can reduce feelings of tension and promote relaxation, which can be beneficial for individuals with certain disorders.

In contrast, the other options describe effects that are characteristic of stimulants rather than depressants. For example, stimulating brain activity would typically lead to increased alertness and energy, which is opposite to the function of depressants. Similarly, increasing heart rate and enhancing sensory perception can result from stimulant use and are not qualities associated with substances that depress central nervous system activity. Therefore, option A accurately reflects the primary purpose of depressants.