Depressants slow down the activity of the central nervous system, slowing down communication between the brain and the body. Depressants are commonly used to alleviate symptoms of anxiety or stress. Prescription medications including benzodiazepines, morphine and codeine are classified as depressant drugs along with illicit drugs such as cannabis, heroin and GHB.
Stimulant drugs increase the activity in the central nervous system, speeding up communication between the brain and the body. Stimulants create a feeling of euphoria and can be used to counter depressive symptoms and low energy. Stimulants include amphetamine type drugs such as ecstasy, speed and ice (crystal methamphetamine) as well as cocaine.
Hallucinogens affect the central nervous system and alter a person's sensory perception. Hallucinogens can be naturally occurring such as the psilocybin found in several types of mushrooms or synthetic such as LSD. Anaesthetics such as PCP and ketamine are also classified as hallucinogens and ecstasy and cannabis can also have hallucinogenic effects when taken in high doses. Often, hallucinogens are used as a complete sensory escape from day to day life.