Seeing something that is not actually there can be deeply unsettling. A flash of light, a shadow, a face, an animal, or even an entire scene may appear completely real in the moment. Yet visual hallucinations are more varied—and medically more complex—than many people realize.

A visual hallucination is a visual experience that occurs without a corresponding external object or stimulus. Most importantly, it is a symptom, not a diagnosis. Visual hallucinations can appear in psychiatric disorders, but they can also be related to neurological conditions, vision loss, sleep disruptions, medications, substances, and other medical problems.

From Flashes of Light to Entire Scenes

Visual hallucinations can be relatively simple or remarkably detailed, spanning a broad spectrum of visual disturbances.

Simple (unformed) hallucinations: These may appear as flashes, sparks, dots, lines, colors, geometric patterns, or vague shapes. A person may describe something that looks like flickering light, mist, or movement without seeing a clearly recognizable object.

Complex (formed) hallucinations: These have a clearer, more defined structure. A person may see animals, people, faces, buildings, landscapes, or complete scenes. The images may involve familiar or unfamiliar individuals and can sometimes become elaborate enough to resemble a moving, continuous scene unfolding right in front of the person.

Because these experiences can differ so much, the clinical details matter immensely. What a person sees, when it happens, how long it lasts, and what other symptoms occur at the same time can give clinicians crucial clues about the possible underlying cause.

Hallucinations Around Sleep

Not every unusual visual experience is a sign of serious mental illness. In fact, many are perfectly benign.

Some people experience exceptionally vivid images while falling asleep or waking up. Hypnagogic hallucinations are those experiences that occur while falling asleep, whereas hypnopompic hallucinations occur during the transition from sleep to wakefulness.

These perceptual anomalies may involve visual images, sounds, or other physical sensations and can frequently occur in individuals without any underlying psychiatric disorder. When they occur exclusively around sleep and there are no other concerning symptoms, they generally fall within the range of normal sleep-related physiological experiences. However, they can also occur more frequently in people with certain sleep disorders, most notably narcolepsy.

When Someone With Poor Vision Sees Things

There is another striking and often misunderstood condition called Charles Bonnet syndrome, in which people with significant vision loss experience visual hallucinations.

They may see intricate patterns, objects, people, animals, or detailed scenes even though those images are not actually present. Critically, people with classic Charles Bonnet syndrome usually retain full insight and awareness that what they are seeing is not real. The experience is neurologically associated with impaired vision and the brain's attempt to fill in missing visual data, rather than a primary psychiatric illness.

This distinction matters profoundly. A person experiencing hallucinations after losing their vision may understandably fear that they are developing a severe psychiatric disorder like schizophrenia, when the underlying explanation is actually entirely different and far more benign in terms of mental health.

When More Than One Sense Is Involved

Hallucinations can also be multimodal, meaning that more than one sensory modality is involved simultaneously.

For example, someone might see a person and also hear that person speaking to them. Another person may see a distinct object and simultaneously experience a smell, a physical touch, or another sensation directly associated with it.

Extensive research in people with psychotic disorders demonstrates that visual hallucinations can, and frequently do, occur together with auditory, tactile, olfactory (smell), and gustatory (taste) hallucinatory experiences.

Visual Hallucinations Do Not Automatically Mean Schizophrenia

One of the most persistent and damaging clinical misconceptions is that hallucinations always indicate schizophrenia. They definitively do not.

Visual hallucinations can certainly occur in schizophrenia and other psychotic disorders, but they are also strongly associated with a vast array of neurological and medical conditions. These underlying causes may include:

• Some forms of dementia and other neurodegenerative diseases (such as Lewy body dementia or Parkinson's disease).
• Epilepsy and specific types of seizure activity.
• Brain lesions, tumors, or strokes.
• Severe acute illnesses affecting overall brain function (delirium).
• Side effects from certain prescribed medications.
• Substance intoxication or severe substance withdrawal.
• Significant vision loss (as seen in Charles Bonnet syndrome).

Furthermore, hallucinations can also appear during severe mood episodes with psychotic features, such as severe depression or bipolar disorder. Their content may sometimes reflect the person's internal emotional state, although this is not a universal rule.

Because there are so many diverse possible causes, the isolated presence of visual hallucinations alone cannot determine a diagnosis.

Treatment Depends on the Cause

There is no single, universal treatment for visual hallucinations themselves, as they are merely a symptom of a deeper physiological or psychological issue.

The foremost task of any medical professional is to fully understand why they are happening. Clinicians must comprehensively evaluate the person's medical and psychiatric history, current medications, substance use, sleep habits, eyesight, cognitive changes, focal neurological symptoms, and the precise characteristics of the hallucinations themselves.

Treatment is then strictly directed at the underlying condition. A medication-related hallucination may simply require a dosage adjustment or medication review. Hallucinations associated with epilepsy, neurodegenerative disease, vision loss, or a primary psychiatric disorder may require vastly different, specialized approaches. While antipsychotic medication may be highly appropriate for certain psychotic conditions, it is not a universal or appropriate treatment for every person who experiences visual hallucinations.

Sudden, new-onset hallucinations accompanied by confusion, fever, severe headache, physical weakness, changes in consciousness, or other new neurological symptoms constitute a medical emergency and deserve prompt, comprehensive medical evaluation.

The most important takeaway is simple: seeing something that is not there does not automatically explain why it is happening. Visual hallucinations are an important physiological or psychological signal that desperately needs clinical context. Understanding that context can successfully replace fear, stigma, and catastrophic assumptions with a much clearer, actionable picture of what may actually be going on.

References

• Teeple RC, Caplan JP, Stern TA. Visual Hallucinations: Differential Diagnosis and Treatment. Primary Care Companion to The Journal of Clinical Psychiatry. 2009;11(1):26–32. doi:10.4088/PCC.08r00673.
  Pages 26–32. A clinical review of the different forms of visual hallucinations, their neurological, psychiatric, medical, sleep-related, and substance-related causes, as well as the importance of determining the underlying condition before choosing treatment.
• O'Brien JT, Taylor JP, Ballard C, et al. Visual Hallucinations in Neurological and Ophthalmological Disease: Pathophysiology and Management. Journal of Neurology, Neurosurgery & Psychiatry. 2020;91(5):512–519. doi:10.1136/jnnp-2019-322702.
  Pages 512–519. Reviews visual hallucinations across neurological and ophthalmological disorders and explains why their characteristics, associated symptoms, and underlying diagnosis should guide management.
• Pang L. Hallucinations Experienced by Visually Impaired: Charles Bonnet Syndrome. Optometry and Vision Science. 2016;93(12):1466–1478. doi:10.1097/OPX.0000000000000959.
  Pages 1466–1478. Focuses on Charles Bonnet syndrome and explains the occurrence of visual hallucinations in people with significant visual impairment, including typical characteristics and clinical considerations.
• Waters F, Ling I, Azimi S, Blom JD. Sleep-Related Hallucinations. Sleep Medicine Clinics. 2024;19(1):143–157. doi:10.1016/j.jsmc.2023.10.008.
  Pages 143–157. Describes hallucinations associated with sleep, particularly hypnagogic and hypnopompic experiences, and explains why these experiences may occur without representing a psychiatric disorder.
• Chouinard VA, Shinn AK, Valeri L, et al. Visual Hallucinations Associated With Multimodal Hallucinations, Suicide Attempts and Morbidity of Illness in Psychotic Disorders. Schizophrenia Research. 2019;208:196–201. doi:10.1016/j.schres.2019.02.022.
  Pages 196–201. Examines visual hallucinations in psychotic disorders and their frequent association with hallucinations involving other sensory modalities, including auditory, tactile, olfactory, and gustatory experiences.