Hallucinations are perceptions of any of the senses without a stimulus: people experiencing hallucinations feel, see, smell, hear, or taste something that is not really there. Illusions, mental images, or imaginative thoughts are often confused with hallucinations, but they are not the same. The defining characteristic of a hallucination is that the person experiencing it believes it is real.
Auditory hallucinations are the most common type. They may manifest as any sound, including music or knocking on a door, but most people hear voices, either distinct or incoherent. These sounds are not the same as the "little voice in your head." The person hears them as external noise, as they would hear any other sound.
Visual hallucinations may appear as beings, objects, patterns, or lights that are not there. They are the second most common type of hallucination and vary significantly. People can see everything from partially or fully formed objects to shadows in their peripheral vision. They may appear as an actual person or something completely abstract.
Tactile hallucinations involve the sense of touch, and people experience them in different ways. Some of the most common are feeling bugs crawling on the skin, being poked or tapped on the shoulder, or being kicked under a table. Tactile hallucinations may also feel internal, such as the movement of organs inside the body.
Hallucinations that involve the sense of smell are olfactory hallucinations. They rarely involve nice smells like flowers or freshly baked bread; instead, individuals usually smell something unpleasant and disturbing. One common example is smelling smoke or fire when the smoke detector is not going off, and there is no danger. Olfactory hallucinations can be pleasant or offensive.
It is a common misconception that hallucinations only happen in conjunction with serious psychotic experiences. The actuality, around 80 percent of hallucinations occur in the general population, are temporary, and happen in passing. Children and the elderly are the most oft-affected, and the events are more common in times of extreme stress, such as fatigue and bereavement.
Alcohol and drugs, such as stimulants and cannabis, can affect the sensory areas of the brain and the central nervous system and lead to hallucinations. Some prescription medications, including those that treat malaria and Parkinson's disease, may also have this side effect. Withdrawal from these substances can cause hallucinations, as well.
Non-mental health medical conditions can cause hallucinations if they interfere with the sensory pathways in the body. For example, deafness can result in auditory hallucinations, and damage to the visual pathways can lead to visual hallucinations. Other possible causes include chromosomal disorders, traumatic brain injuries, sleep disorders, Alzheimer's disease, seizures, and some vitamin deficiencies. People with migraine headaches can experience visual hallucinations before or during a migraine.
Most people first think of the psychiatric conditions known to cause hallucinations. While the events are most closely associated with extreme psychotic disorders like schizophrenia and other schizoaffective diagnoses, hallucinations can also result from spectrum disorders, depression, PTSD, anorexia, bulimia, or the manic, mixed, and the depression phase of bipolar disorder.
Experts recommend immediate medical attention for anyone who experiences hallucinations; some causes can quickly become medical emergencies. For example, someone smelling something that isn't there may be having a stroke. People experiencing hallucinations should not be left alone.
Treatment for hallucinations depends on the cause. The physician may perform blood tests, brain scans, or general observation. If medication or drug use is causing the events, ceasing the substance often eliminates the hallucinations. Likewise, when medical conditions cause them, treatment for the underlying cause generally reduces or eliminates instances. In the case of a psychotic disorder, medication or dosage adjustments of current medication may be necessary.
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