Depressants are psychoactive drugs that slow down the activity of the central nervous system (the brain and spinal cord), which reduces a person's alertness, and also slows down functions such as breathing and heart rate. These can take the form of pharmaceutical drugs as well as illicit substances. Alcohol is also a widely used depressant.
Examples of depressant drugs:
In small quantities depressants can cause a person to feel more relaxed. In large quantities they can cause unconsciousness, vomiting and death. Mixing more than one depressant is dangerous as this can make it harder to think clearly, properly control how you move and may stop your breathing and cause death.