Introduction

Sleep hallucinations are surreal visual and sensory perceptions that may be experienced when someone is asleep. These perceptions are false and have no external stimuli in the environment. However, since they seem to be real to the individuals that experience them, they can be terrifying and cause fear responses. Sleep hallucinations are commonly symptomatic of other medical conditions, including mental illnesses and other sleep disorders, such as narcolepsy, insomnia, and sleep deprivation. They can also occur as a solitary disorder.

Sleep hallucinations occur as the body undergoes transitions between wakefulness and sleep. During these transitions, the brain is alert to internal mental processes which may lead to mental perceptions to be interpreted as stimuli from the surroundings. Based on the type of transition, sleep hallucinations are classified into two:

  1. Hypnagogic hallucinations – These hallucinations occur as the body transitions from wakefulness to sleep.
  2. Hypnopompic hallucinations – These hallucinations occur during the transitions from sleep to wakefulness. They appear as a continuation of a person’s dream sequence.

Sleep hallucinations that are not caused by any underlying condition frequently resolve after a short while without the need for medication.  Treatment becomes necessary when sleep hallucinations affect one’s sleep and lead to other complications, such as stress and anxiety.

Symptoms of sleep hallucinations

Sleep hallucinations are imaginary sensations that are different from dreams since they appear as real experiences to people. Hence, they lead to people having a certainty that they have seen, heard or felt something while asleep. Therefore, the most common symptoms of sleep hallucinations include the following:

1. Visual hallucinations symptoms

Visual hallucinations appear in kaleidoscopic forms containing changes in light and shapes. The individual sees geometric patterns, light flashes, and life like images, such as animals and people. The images are often colorful and detailed. Visual hallucinations are the most common sleep hallucinations and are reported in up to 86% of all hypnagogia cases.

2. Auditory hallucinations symptoms

Auditory hallucinations comprise imagined perceptions of sound which occur with no auditory stimuli present. They are often viewed as internal sounds because they do not originate from the surrounding environment. A person experiencing auditory sleep hallucinations hears strong auditory sensations, such as the sounds of people talking, environmental sounds, and animal sounds. Some people report hearing distinctive sounds such as their names being called.

3. Tactile hallucinations symptoms

These are hallucinations that involve the sense of touch. The individual with the disorder gets false perceptions of physical contact with objects in the environment that are imagined. Commonly reported tactile hallucinations include insects crawling on the skin or in the body, which sometimes leads to itchiness. Tactile hallucinations are not as common as visual and auditory sleep hallucinations.

Causes of sleep hallucinations

Sleep hallucinations are not well-understood phenomena and, therefore, their causes, especially in people with no underlying medical conditions might vary. They are, however, thought to be caused by an overlap in the deep sleep and light sleep phases. Sleep hallucinations frequently occur as symptoms of other medical conditions, such as mental illnesses and sleep disorders. The common causes of sleep hallucinations are:

1. Alterations in Serotonin 2A receptors

Serotonin 2A receptors are found in the visual cortex and play a significant role in processing images. Studies show that individuals who experience visual hallucinations have alterations in these receptors. This is commonly observed in people who have Parkinson’s disease and schizophrenia. Alterations in serotonin 2A receptors lead to the same effects as those induced by hallucinogens, such as psilocybin (psychedelic mushroom) and lysergic acid diethylamide (LSD). They cause excitation in the cortex, thus altering an individual’s vision and leading to visual hallucinations.

2. Mental conditions

Mental conditions such as schizophrenia, clinical depression, bipolar disorder, and anxiety disorders are known to cause hallucinations when both awake and asleep. Hallucinations are significant symptoms used in the diagnosis of schizophrenia because the condition is commonly associated with delusions and experiences that are imagined, such as hearing voices. Sleep hallucinations are also frequently reported in cases of clinical depression and are used in diagnosing many other mental conditions.

3. Other sleep disorders

Sleep hallucinations are commonly associated with narcolepsy, which is a sleep disorder that causes abnormalities in the sleep-wake states and leads to excessive sleepiness.  The disorder causes a mix-up in the states of sleep and wakefulness, thus causing an individual to experience rapid eye movement during sleep while in an intermediate state of wakefulness. Thus, it leads to dreams appearing more real as the brain is alert to internal mental processes while one is still asleep.

4. Progressive neurological conditions

Many neurological conditions, such as Alzheimer’s and Parkinson’s diseases, are associated with sleeping disorders. Patients of these diseases have reported having vivid dreams and increased movement when asleep. Sleep hallucinations are most frequently reported in cases of Parkinson’s disease. These hallucinations are mainly visual and can be debilitating to an individual.

5. Melatonin suppression

Studies have shown that melatonin suppression is likely to cause nocturnal visual hallucinations. The mechanism that leads to this response is still not well-understood as researchers have come with few and contradictory findings. It is, however, speculated that the alteration of an individual’s sleep patterns due to the lack of melatonin causes a response in the form of complex hallucinations.

6. Illicit drugs and alcohol

Illicit drugs are taken due to their psychoactive properties that alter the mind. Common illicit drugs, such as lysergic acid diethylamide (LSD), ecstasy, and cocaine are known to cause hallucinations. The consumption of alcohol and withdrawal can also lead to hallucinations. Most of the sleep hallucinations caused by drugs and alcohol are visual.

7. Prescription Medication

Prescribed drugs can have side effects that affect one’s sleep. This is especially seen in medications for psychiatric conditions. For example, people who are under tricyclic antidepressants report frequent sleep hallucinations. Most psychiatric drugs work by increasing dopamine levels, which can lead to hallucinations. Other prescribed medications that can cause sleep hallucinations include sedatives, anti-seizure drugs, steroids, and narcotics.

Diagnosis

Sleep hallucinations are diagnosed based on the information provided by the individual or their close ones and a review of one’s medical history. The doctor assesses the following:

  • Sleep-wake habits
  • Present health condition
  • Current medications
  • Drug and alcohol use
  • Possible head trauma
  • History of the symptoms

In a positive diagnosis of sleep hallucinations, the individual has recurrent hallucinations a short while before sleeping or just after waking up. These sleep hallucinations are visual in most cases. The presence of other medical conditions including other sleep disorders, mental conditions, and progressive neurological disorders that cause sleep hallucinations, can also lead to a positive diagnosis. Doctors use different tools in the diagnosis, including:

1. Sleep diary

The doctor asks the individual to keep a sleep diary, usually for two weeks, with records of sleep and wake times. It is used to assess one’s sleep habits.

2. Polysomnogram (PSG)

A polysomnogram, also known as a sleep study, is carried out using diagnostic equipment that is attached to the head and body.  It records a person’s brain waves, breathing, heartbeat, and limb movement; thus, it can detect sleep hallucinations.

3. Multiple sleep latency test

The latency test shows the time taken by an individual to fall asleep. It is commonly used to determine whether one’s sleep hallucinations are associated with other sleep disorders, such as narcolepsy and hypersomnia.

4. CT scan and MRI

They are brain scans that are carried to show the electrical activity of the individual’s brain when asleep.

 

One needs to seek medical assistance when they experience recurrent sleep hallucinations. Many people are reluctant to seek help because hallucinations are stigmatized as a sign of insanity. Informing a physician can help obtain a proper diagnosis and timely treatment.

Treatment

There is currently no particular treatment for sleep hallucinations as a distinct disorder. Treating sleep hallucinations mainly involves treating the underlying condition causing them. The treatment that is chosen by the doctor, therefore, varies for each case. For example, an individual with a mental illness, such as schizophrenia, is treated using antipsychotic drugs. On the other hand, an individual with a progressive neurological condition, such as Parkinson’s disease, may need to have changes in their medications as the treatments used for these conditions cause hallucinations.

Several new medications have shown significant potential in treating sleep hallucinations as a distinct disorder, although they are still being studied and tested. They include:

a) Pimavanserin

Pimavanserin is a serotonin 5-HT2A receptor inverse agonist. It is used to treat visual hallucinations caused by alterations in serotonin 2A receptors. Changes in these receptors have been shown to cause visual hallucinations that are quite similar to those caused by hallucinogens and lead to fear responses.

b) Ketanserin

Ketanserin is a 5-HT2A receptor antagonist, which works by blocking sleep hallucinations, especially those that are associated with sleep paralysis. It is an antihypertensive drug and that is useful in treating hallucinations associated with hallucinogenic drugs, such as psilocybin.

c) Melatonin therapy

Some researchers have found that melatonin therapy may be an effective method for treating sleep hallucinations. The mechanism involved in the treatment is not clear, but the patients involved in the research study showed significant improvement when treated with melatonin supplements. The therapy led to fewer awakenings in the night, reduced sleep latency, increased sleep quality, and longer sleep duration. Further, the patients reportedly stopped experiencing sleep hallucinations.

Natural treatment options

Several treatment options for sleep hallucinations are non-medicinal. They include:

1. Cognitive-behavioral therapy

Cognitive-behavioral therapy is a form of psychotherapy used to help one to understand the experiences that they are going through. It helps the individual think constructively and avoid destructive behavior. This intervention is highly effective in improving sleep in individuals who deal with sleep disorders. It improves sleep quality, thus reducing sleep hallucinations. Going through this therapy also helps the person and those close to them deal with the stress and stigma caused by the hallucinations.

2. Lifestyle changes

Sleep hallucinations do not require treatment if they are infrequent and do not have an underlying medical condition. The occurrence of these hallucinations tends to decrease with time and the problem can resolve on its own. Several lifestyle changes can help improve the condition and make the individual more comfortable. They include:

  • Getting adequate sleep
  • Having a regular sleep schedule
  • Avoiding illicit drugs and alcohol
  • Avoiding stress

3. Care from friends and family

One can benefit from the comfort of friends and family because the condition is associated with a lot of stress and stigma. Being around supportive people can help the individual as they go through the condition.  It is important to take care of an individual who experiences sleep hallucinations and avoid leaving them alone. Some hallucinations can lead to significant fear responses, some of which can cause serious injury or even death.  Remember the hallucinations appear real to the individual, thus causing fright and confusion. Therefore, people with the condition need to be calmed or distracted from their ordeals.

Conclusion

Sleep hallucinations are imagined sensations that occur when someone is asleep, and they are not similar to dreams. They commonly occur in visual, auditory, and tactile forms.

Sleep hallucinations seem real to the individual although they are not the result of any external stimuli. They can cause fear and confusion to both a patient and those around him or her.

Sleep hallucinations mostly occur with other medical conditions, especially mental illnesses, progressive neurological conditions, and sleep disorders. They can also occur as a solitary disorder but in most cases, they are symptomatic of other health issues.

Other common causes of sleep hallucinations are alterations in serotonin 2A receptors, melatonin suppression, the use of illicit drugs, alcohol, and some prescription medications.

In the diagnosis of sleep hallucinations, the doctor analyzes the patient’s medical history and present state thoroughly to identify other underlying conditions that may be causing them.

A positive diagnosis of sleep hallucinations is made when the individual is found to have recurrent hallucinations when asleep. The diagnosis is carried out using different tools, including a sleep diary, polysomnogram, multiple sleep latency tests, and brain scans.

There is no specific treatment for sleep hallucinations and, therefore, they are mainly treated by addressing the underlying medical condition. Several new medications, such as pimavanserin, ketanserin, and melatonin supplements, are being studied and tested in the treatment of solitary cases of sleep hallucinations. Currently, cognitive behavioral therapy, lifestyle changes and support systems from friends and family have been very effective in controlling the condition.

 

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