Hypnagogic hallucinations are imaginary images or sensations that seem real and occur as a person is falling asleep. These are different from dreams, which a person experiences while fully asleep.

The term hypnopompic describes the period when a person wakes up. Hypnagogic defines the period when a person falls asleep. A hallucination is anything that can be sensed but is not real.

Sleep-related hallucinations are common in the general population and can take various forms.

In this article, we cover the causes, symptoms, and complications of hypnagogic hallucinations.

A note about sex and gender

Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

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Researchers have not uncovered the exact cause of hypnagogic hallucinations. These hallucinations can be the result of narcolepsy, a condition that causes people to fall asleep suddenly. The rapid descent into REM sleep may be a factor in hypnagogic hallucinations.

Aside from narcolepsy, hypnagogic hallucinations may have links with Parkinson’s disease and schizophrenia.

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A person will experience vivid hallucinations as they fall asleep or just before falling asleep. These can be images, smells, tastes, tactile sensations, or sounds.

A person may also feel as though they are moving while their body is still. This sensation could be a feeling of falling or flying.

Visual hallucinations

During hypnagogic hallucinations, people will often experience visual disturbances. They may include images of people, animals, or moving objects.

Images can be quite complex and detailed or may simply appear as blurs or misperceptions.

Audio hallucinations

Hypnagogic hallucinations often have an auditory component. The extra content of these sounds may vary between people.

People may feel as though they can hear voices, environmental sounds, or unidentifiable noises.

Other symptoms

During a hypnagogic hallucination, a person knows that they are awake. The images, sounds, or other sensations may last a number of minutes. They may prevent a person from falling asleep.

These hallucinations may happen at the same time as sleep paralysis.

Learn more about hallucinations here.

Certain factors may increase the likelihood of experiencing hallucinations.

They tend to occur less frequently as a person ages, and women are more likely to experience these hallucinations than men.

If a person uses drugs or alcohol, they may be more likely to experience hypnagogic hallucinations. The condition also has links with anxiety and insomnia.

Hypnagogic hallucinations are not usually a health risk.

Certain medical conditions have links with these hallucinations. If a person has any of the following symptoms, they may wish to contact a doctor.

  • Symptoms of narcolepsy: These include muscle weakness, being very sleepy during the day, and having disturbed sleep at night.
  • Symptoms of schizophrenia: These include hearing voices, having confused thoughts, and experiencing changes in behavior.
  • Symptoms of Parkinson’s disease: These include slow movement, muscle stiffness, and shaking in the hands and other parts of the body.

A migraine episode may also cause a person to see colors, lights, or images that do not exist. These visualizations are called auras. They usually occur alongside a migraine headache and are different from hallucinations.

Hypnagogic hallucinations can be disturbing. They can stop a person from sleeping well and cause stress or anxiety. If this is the case, a person may wish to contact a doctor.

If a person experiences hypnagogic hallucinations alongside narcolepsy, schizophrenia, or another related condition, treatment will focus on managing these associated conditions.

Prevention strategies

If a person’s quality of life is not affected by their hypnagogic hallucinations, they may not need treatment. And if there is no underlying medical condition, lifestyle changes may reduce the frequency of hallucinations.

Getting enough sleep and avoiding drugs and alcohol can reduce their frequency. If hypnagogic hallucinations cause disrupted sleep or anxiety, a doctor might prescribe medication.

Learn about good sleep habits here.

When these hallucinations are often not the result of an underlying condition, they usually do not have long-term complications. Their most common effects are disturbed sleep and stress or anxiety.

Learn more about the symptoms of sleep deprivation here.

However, hypnagogic hallucinations can cause a person to wake in terror and scream or shout, which may disturb a partner or roommate. Also, a person experiencing a hallucination may fall out of bed or otherwise injure themselves.

Many of these issues can harm health and well-being. A person may wish to consult a doctor for advice or treatment.

During sleep, many parts of the brain are still active. Processes such as breathing and circulation continue to function.

Sleepwalking, nightmares, sleep paralysis, and similar experiences are known as parasomnia. Often there is no known cause, but parasomnia can run in families.

As a person falls asleep or wakes up, they will usually enter a period of lighter sleep. Narcolepsy can cause a person to enter directly into a period of deeper sleep or wake up in the middle of one. This may cause dreams or hallucinations to feel more real.

Hypnagogic hallucinations tend to have no long-term side effects. They often happen because of an underlying medical condition or during periods of poor sleep and stress.

Getting advice and treatment for an underlying condition can help to reduce the frequency of hypnagogic hallucinations.

Making changes to a sleep schedule and getting more rest will often resolve the condition.