The phrase "system depressant" refers to a substance that slows down or suppresses the normal functioning of the body's systems, such as the central nervous system. It can make a person feel relaxed, calm, and less alert. Full definition
Phenibut is a central nervous system depressant with anxiolytic (anti anxiety) and sedative effects which is used for the treatment of anxiety, insomnia, and a variety of other indications in some countries. (ronniecoleman.net)
The barbiturates were the most versatile nervous system depressants available during the first half of the twentieth century. (discovermagazine.com)
Dogs taking central nervous system depressants like Valium will see increased effects like excessive drowsiness, loss of coordination, or even unconsciousness. (smartdogowners.com)