Depressors are substances that decrease the level of activity in the brain, slowing down the body. The most commonly used depressants generally fall into two classes, barbiturates and benzodiazepines. Depressants include alcohol, narcotics, sedative hypnotics, first-generation antihistamines, and some anesthetics. They have the ability to slow brain activity, causing drowsiness, decreased heart rate, pain relief, decreased breathing, and body paralysis.
