What Exactly Is a Hallucination?

A hallucination (pronounced hal-oo-sin-A-shun) is something you see, hear, feel, smell, or taste that isn't really there. Hallucinations can happen through any of the five senses, but the most common types are visual and auditory (hearing) hallucinations.

Hallucinations can happen under the influence of drugs, especially hallucinogenic or psychedelic drugs, such as LSD or magic mushrooms. Hallucinations can be a symptom of psychosis as well. This includes is a group of serious symptoms of mental illnesses, such as schizophrenia or bipolar disorder.

In addition, hallucinations can happen to almost anyone if they are subjected to extreme physical or mental stress. A person may also hallucinate when they are extremely sleep deprived.

Visual hallucinations can include mild distortions of what you see around you. People who use hallucinogenic drugs often describe these mild distortions as pleasant.

It might include experiences such as:

• Colors appearing more vivid.
• Seeing halos around objects.
• Experiencing visual illusions more clearly.
• Seeing things differently in your peripheral vision.
• Seeing faces as looking artificial or made of plastic, clay, or some other inanimate substance.
• Seeing walls appear as if they are "breathing."
• Noticing patterns that had not been apparent before. These may be through naturally occurring patterns, such as the veins on a leaf, or patterns superimposed onto objects.
• Seeing entire objects or people who are not really there. This can sometimes be confusing to the person seeing them.

Visual hallucinations are a hallmark effect of hallucinogenic drugs, such as LSD. The extent to which people experience hallucinations while under the influence of these drugs varies.

Some people see these "visuals" consistently on low doses of the drug, while other people experience only a stimulant effect, even on quite high doses. This can also change rapidly within the same drug experience. People who have never hallucinated before may suddenly find themselves in an alien, seemingly make-believe world.

Visual hallucinations can be pleasant or unpleasant. They can quickly shift from one to the other, causing rapid shifts in mood.

Auditory hallucinations can range from mild distortions in what you hear to hearing voices when nobody is speaking. The voices may be quiet or loud, friendly or intimidating.

Auditory hallucinations are the most common type of hallucination experienced by people dealing with schizophrenia. Distortions to sounds and the intensity of auditory experiences, such as listening to music, is common on hallucinogenic drugs.

Tactile hallucinations are physical sensations of something that is not there. Mild tactile hallucinations are common in people high on psychoactive drugs. However, they are not always pleasurable or mild. All of these drugs are unpredictable and vary in effect from one person to another.

Crystal meth is notorious for producing unpleasant tactile hallucinations. Users often feel as if bugs are crawling over or underneath their skin. These tactile hallucinations can feel so real to a meth user that they scratch or pick holes in their skin while trying to remove the bug. This can lead to sores, scabs, scars, and infections.

Olfactory hallucinations mean that someone smells something that is not there. Taste hallucinations are quite rare and may also be experienced, although these have not been the subject of much interest.

Like other hallucinations, olfactory and taste hallucinations can be troubling to the person experiencing them, especially if they overlap with delusions. For example, in a person who has a delusion that he is being poisoned, a taste hallucination would be extremely distressing. The person might perceive it as proof that the delusion is true.