Causes Of Hallucinations And Theories Explaining It

Causes of hallucinations

The mind is indeed beautiful. To think that artists, scientists, players, musicians, and prodigies possess a similarly structured brain is a tell-tale of how complicated the brain really is. Consciousness, subconsciousness, dreams, imagination – so much going on in one organ!

Hallucinations are not illusions or delusions.

  • Illusion: A reasonable misinterpretation of a real sensation, like in 3D-paintings.
  • Delusion: A misinterpretation of a real sensation despite there being contradictory evidence.

Now, what if the boundary between our consciousness and subconsciousness was blurred? What if we physically reacted to something we thought was real? That’s exactly what hallucinations are – real reactions to unreal sensations. A host of triggers including migraines, high fever, and even unsuspecting sleep can interfere with our interpretation of reality.

You Cannot Dream Or Imagine Hallucinations


Hallucinations are different from dreams or something imagined. They are way more detailed than dreams, and unlike our imagination, they are unintended and uncontrollable. They can affect all five of our senses, are person-specific, sudden, and not a mere symptom of madness. They can be comforting and pleasant, frightening and threatening, or plain neutral.

You Cannot Dream Or Imagine Hallucinations

Hallucinations are subconscious thoughts that we externalize and fail to recognize as thoughts. From swirly shapes while rubbing your eyes to seeing floating handkerchiefs to preparing dinner for a guest you think is real, hallucinations can take various forms and complexities.

Type Of Hallucination Common examples
Auditory Hearing music, the door knock, the phone ring, or a voice
Visual Seeing a white light, geometrical shapes, figures, faces, or shadows
Olfactory Smelling smoke, burnt toast, or something foul
Tactile Feeling something (insects, snakes) crawling on or under your skin
Gustatory Food tasting rotten or unpleasant when it is actually not

Causes Of Hallucinations


The term hallucination invokes a certain discomfort, suspicion of madness, or even an irresistible insight into the spiritual realm in most people, which is why it is such a social stigma. Funnily enough, terms like apparitions, phantoms, and ghosts – essentially the same as hallucinations – are socially more acceptable. What we must realize is that hallucinations are not always a result of psychosis, particularly schizophrenia, and it is way more common than we’d like to admit.

Here are the most common causes of hallucinations:

1. Sleep-wake Transitions

When you wake up from a nightmare, you know that you were sleeping when you had it. That sense of awareness is missing in sleep hallucinations.


Sleep-related hallucinations, mostly linked with lack of sleep, are projections of our mind that occur as we transition in and out of sleep. You won’t be able to tell if you are dreaming or experiencing something real. These hallucinations are mostly visual and may be something very bizarre.

There are two types:

  • Hypnagogic hallucinations: Just before falling asleep, in 37% of the general population, usually no emotional involvement1
  • Hypnopompic hallucinations: While waking up, in 12.5% of the general population, usually demands emotional involvement like fear2

Because we may fall in and out of sleep multiple times through the night, most often it is difficult to distinguish between hypnagogic and hypnopompic hallucinations. Both types are seen to decline with age in adulthood.3

If you hallucinate during the day, it may be an indication that you are suffering from narcolepsy (excessive daytime drowsiness).4

Association with narcolepsy: Sleep hallucinations are not only restricted to the night. If you suffer from narcolepsy or daytime drowsiness and fall in and out of asleep, you may hallucinate during the day as well.


Association with sleep paralysis: Sleep hallucinations often accompany sleep paralysis. While the hallucinations startle you awake with sounds, voices, or figures, sleep paralysis makes you feel tied down – quite a scary experience.

2. Bereavement

One in two people in long, happy marriages have been shown to experience visual or auditory hallucinations after the demise of their spouses.5 This may even involve a full-fledged conversation between the living spouse and the deceased one. This can be seen as an adaptive technique during the grieving period.

3. Post-Traumatic Stress Disorder (PTSD)


Auditory hallucinations can be a result of past traumatic experiences.6 These are often seen in combat veterans and children who have been sexually abused.

4. Delirium

Delirium is a confused, excited state of a person commonly brought on by high fever, infections, alcohol withdrawal (delirium tremens), and stimulant intoxication (cocaine, methamphetamine).7 8 Delirious individuals often experience visual hallucinations. In children with high fever, these are often associated with sleep.9

5. Migraines


About 1 in 3 people with migraines experience a visual aura.10 They see a flickering, uncolored, zig-zag line moving from the center of their visual field toward the periphery. Hallucinations lasts for about half an hour.

6. Sensory Deprivation

Loss or weakening of any of our five senses can force the part of the brain responsible for that sense to become hyperactive and cause hallucinations.11 For instance, as people lose their sense of hearing, they may begin to hear sounds and voices that, in reality, is being fabricated by their brain. You don’t have to be completely deaf or blind, just sufficiently impaired. This can also explain why people who have amputated a limb continue to feel movement and even pain.12

7. Psychoactive Substance Intoxication

Psychoactive Substance Intoxication Causes Hallucinations

Scarily, a person can have flashbacks of hallucinations experienced during the ingestion of a drug months later when not on the drug.13

  • Drugs: Hallucinogens are found naturally in some plants (cannabis) and mushrooms (magic mushrooms) and have been used for centuries in religious and spiritual rituals. Depending on dosage, mood, and situation, psychoactive substances like mescaline, psilocybin, dimethyltryptamine (DMT), lysergic acid diethylamide (LSD), cocaine, amphetamine can cause hallucinations.14 Colorful visuals, indistinct noises, and the feeling of insects crawling on your skin are common.
  • Alcohol: Mostly auditory but also visual and tactile, alcohol-induced hallucinations occur (alcohol hallucinosis) while or after consuming excessive alcohol.1516 They are often accompanied by mood swings and delusions.

8. Epileptic Seizures

Epileptic seizures trigger a sudden, explosive firing in a specific part of the brain causing one to hallucinate. These hallucinations are mostly visual and simple in nature, like flashes of light or brightly colored spots.17

9. Psychosis

According to The Diagnostic and Statistical Manual of Mental Disorders, hallucinations is a primary criterion in the diagnosis of various psychotic disorders – mental disorders that disconnect you with reality.18 Most psychotic hallucinations are auditory. Psychotic disorders causing hallucinations are:

  • Schizophrenia: A whopping 70% of schizophrenics have hallucinations – mostly auditory, followed by visual.19 The hallucinations have an unreal quality about them, often involving only parts of people, fragments of objects, and scenarios that are not of this world. Family members, religious figures, and animals are often reflected in visual hallucinations.20
  • Psychotic depression: This is a severe form of major depressive disorder in which depressed individuals have hallucinations.21
  • Postpartum psychosis: New mothers suffering from postpartum psychosis may have tormenting hallucinations where they hear or see people telling them they are not good mothers or that they should kill their baby.22

Linked with psychosis, borderline personality disorder (BPD) too causes hallucinations. About 30% patients with BPD have hallucinations.23 The hallucinations are similar to those experienced by schizophrenics but tend to be more negative and distressful.

Does Anxiety Cause Hallucinations?

It can, but only severe anxiety and rarely.24 Also, severe anxiety may be a symptom of another underlying mental disorder, like schizophrenia, and may not be the actual trigger for the hallucination. One study suggests that anxiety not only causes one to hear voices, but also determines their content, mostly negative in nature.25

Hallucinations In Children

It can be tricky to understand whether or not your child is hallucinating. Self-talk, imaginary friends, and problems to express can be easily misinterpreted as hallucinations. Encourage your child to express themselves the best way they can and keenly monitor their behavior at all times to catch hints of true hallucinations.

Keeping in mind the social demonization of hallucinations, it is but natural that parents worry themselves sick if their children report seeing or hearing things that are not really there. Parents, as you now know, hallucinations are not always linked to a mental disorder. In children, they are not uncommon and are often a result of normal development.26

  • Children below 7 years may struggle to distinguish between regular dreams and reality.
  • Often a child acting out (as in ADHD and oppositional defiant disorder) may blame “voices” for their misbehavior.
  • Children struggling with speech may call their thoughts “voices.”
  • Adults may misinterpret normal self-talk as auditory hallucinations.
  • By 7 years of age, 37% children create imaginary friends. As is obvious from the term, these are projections of a child’s imagination as a normal coping mechanism, like self-talk.27 28 They can be invoked and controlled unlike hallucinations.29

Sleep-related hallucinations or those resulting from high fever are not a major cause for concern. In about 50-95% children, hallucinations cease in a few weeks or months. However, hallucinations persisting into adolescence may be indicative of more serious conditions like:

  • Psychosis like childhood-onset schizophrenia (typically before 13 years of age)
  • Mood disorders like attention deficit hyperactivity disorder (ADHD), major depressive disorder (MDD), and disruptive behavioral disorders

Childhood trauma (sexual, physical, or emotional abuse, bullying or neglect) and genetic predisposition are risk factors for psychotic hallucinations in children.30 Culture and religion have strong influences on what a child hallucinates.

Theories Explaining Hallucinations

Now that we have some understanding about hallucinations, let’s dig a little deeper to know how scientific greats have explained this phenomenon.

Culture Influences Hallucinations
People around the world see different hallucinations – angels, devils, monsters, goblins, aliens, and all kinds of mystical creatures. A person in Norway may see trolls while one in Ireland sees leprechauns.

  • Freudian theory: Hallucinations are, like dreams, projections of the subconscious – unfulfilled wishes, guilt, self critique, and suppressed emotions – and are purely triggered by psychology.31 Despite biological theories being more popular among scientists, the Freudian theories explain the content of hallucinations better – why hallucinations are different for different people in similar situations. For example, Lilliputian hallucinations involves seeing small people or animals. The kind of people you see will depend on what you’re familiar with, on your culture and upbringing.
  • Neurophysiologic hypothesis: Abnormal brain excitation, disconnects between different parts of the brain (primary sensory cortex and influencing areas), and information from overpowering memories have been implicated in hallucinations.32 For instance, musical hallucinations may just be the strengthening of memories of tunes heard in the past.
  • Neurotransmitter hypothesis: Imbalance of neurotransmitters dopamine, acetylcholine, serotonin, glutamate, and GABA-A can cause you to hallucinate.33
  • Morrison’s hallucination model: When you have two conflicting thoughts – one that is unintended and one that you think you should think (metacognition), you hallucinate to justify the unintended thought.34 For example, if you feel like screaming during class, but you believe you are not the kind of person who would do that, you may hear a voice or see a figure telling you to go ahead and scream. In this way, the blame will not be “technically” yours, allowing you to believe that you stuck to your belief system. You pass the buck on to a figment of your subconscious.

When To Seek Help

If you or a loved one is hallucinating while falling asleep, while waking up, when stressed or tired, or when delirious, it’s okay to wait out the hallucinations. Even then, it’s advisable to tell someone about it. However, if the hallucinations start interfering with regular day-to-day activities, it’s best to immediately seek medical help.

Because hallucinations can be intimidating, frightening, and even nerve-racking, it’s important that persons experiencing them constantly be in the company of people they trust.