A A hallucination is a perception that has qualities of real perception without an external cause. Hallucinations occur while awake and are not under voluntary control. Hallucinations can affect any of the five senses — sight, hearing, smelling, taste, and touch. Hallucinations can be associated with drug use, sleep deprivation, psychosis, neurological and psychiatric disorders, and delirium tremens — a complication of extreme amounts of alcohol intake.
A hallucinogen is a psychoactive substance that can alter a person’s mood, behavior, and perception of reality, and the hallucinations can range in severity from mild to intense. There are a variety of “natural” (e.g. the peyote plant) and synthetic (e.g. LSD) hallucinogens available.
The common classifications for hallucinogens are:
- Psychedelics – like LSD and psilocybin
- Dissociatives – like ketamine
- Deliriants like diphenhydramine – Deliriants cause delirium or an acute confusional state, and this primary effect distinguishes them from psychedelics and dissociatives, which are characterized by clearer states.