What Are Hypnopompic and Hypnagogic Hallucinations?

The sleep cycle involves a series of transitional states that repeat themselves throughout the hours that you're sleeping. It's not uncommon for people to experience a type of hallucination while falling asleep or after waking, though there are conditions like narcolepsy that may make it more likely.

Hypnopompic hallucinations typically occur as you're waking up. They're mostly visual, and may feel as if your dream state is continuing into your wakefulness, as with lucid dreaming. Hypnagogic hallucinations are similar but more often occur as you're falling asleep.

This article explains how people may experience these sleep-related hallucinations and some of the behaviors seen with them. It explains medical conditions that may make these episodes more likely.

Sleep Cycles

There are four distinct stages that occur during sleep and they repeat themselves in cycles until you are awake. The sleep stages fall into two categories called:

• Non-rapid eye movement (NREM) sleep, the quiet sleep of stages 1 through 3
• Rapid eye movement (REM) sleep, the active sleep stage in which dreams occur

The typical pattern of these stages moves from stage 1, as you begin sleeping, to stage 2 and then stage 3. You then return to stage 2, repeat the cycle, and eventually reach REM sleep.

However, the sleep cycle often is disrupted in sleep disorders or, in some cases, due to other medical conditions. It also is unique in some way to each person, a feature that specialists refer to as sleep architecture.

A hypnagogic hallucination is likely to occur in the first stage of sleep as brain activity changes, while hypnopompic hallucinations often feel like the continuation of a dream sequence during those first few seconds or minutes as you transition from sleep into an awakened state.

Symptoms

When people report hallucinations, they often describe visual experiences. They see something that isn’t there, or they misinterpret something in the environment, also referred to as an illusion.

Other hallucinations involve auditory experiences, meaning that a person hears things instead. In some cases, the hallucination may feel like a sense of falling or other movement.

Hallucinations may occur along with other symptoms, such as sleep paralysis. Waking from this immobile state may cause a startle. Some people may jump up in bed or engage in behaviors like sleepwalking and sleep talking. Research shows that nearly 70% of adults sleep talk at some point in their lives.

A study of 2,533 Norwegians found that slightly more than half of them had hallucinations of some type while falling asleep or waking. Of those who did:

• 173 people, or 6.8%, said they experience auditory hallucinations.
• 312 people, or 12.3%, said they see or feel something that's not there.
• 816 people, or 32.2%, had motion-related experiences, as if falling or floating.

Causes

Hallucinations may simply represent the persistence of dream imagery into wakefulness. While this may be a typical phenomenon in sleep-wake transitions, it also occurs in the context of specific medical conditions and may be considered part of a pattern of symptoms that arise with them.

Sleep Deprivation

When people aren't getting enough sleep to meet the physical and mental needs of their bodies, they experience sleep deprivation. This leads to fatigue but also more serious issues, including:

• Heightened sensitivity to pain, and chronic pain conditions
• Hormonal changes, including thyroid disorders
• Hallucinations in the context of extreme sleep deprivation

One of the most comprehensive studies of how sleep deprivation affects mental health, including symptoms like hallucinations, involved 261,547 adults from 56 countries. People who were sleep deprived were more than twice as likely to say they experienced hallucinations or had delusions that someone wanted to hurt them.

Narcolepsy

The presence of hypnagogic hallucinations as you fall asleep is considered one of the cardinal signs of narcolepsy, which affects up to one in every 2,000 people. Their hallucinations tend to be visual, vivid, and may be mixed with other types of hallucinations, including hypnopompic.

People with narcolepsy also may experience symptoms of:

• Fragmented sleep, which causes disruptions in the sleep cycle
• Excessive daytime sleepiness
• Sleep paralysis
• Cataplexy, which are sudden bouts of muscle weakness

There is no cure for narcolepsy, but it can be managed with medication and lifestyle changes. These may include getting more physical exercise and improving sleep hygiene with a set sleep schedule and improvements in your sleep environment.

Other Sleep Disorders

A number of sleep disorders may contribute to the conditions that can lead to hypnagogic and hypnopompic hallucinations, or be related to them. They include:

• Obstructive sleep apnea, which causes breathing difficulties while sleeping
• Restless legs syndrome, which causes leg discomfort and motion while sleeping
• Circadian disorders, which causes your "body clock" to be out of alignment with your sleep hours

These sleep disorders may lead to sleep deprivation or excessive daytime sleepiness, which in turn may raise the risk of hallucinations.

Parkinson's Disease

Complex types of sleep hallucinations are somewhat rare and may suggest the possible presence of a neurologic disorder, such as Parkinson’s disease or dementia with Lewy bodies.

Mild hallucinations are the most common type associated with Parkinson's disease, and they tend to be visual in nature. They are viewed as a sign of a higher risk of more serious psychiatric conditions in people living with Parkinson's.

Medications

Both visual and hearing-related hallucinations may be possible due to medication use. That's especially true with drug interactions that occur when more than one drug is in use.

Medical researchers have confirmed cases in which drug interactions have led to hallucinations in people being treated for:

• Chronic pain, when the narcotic Ultram (tramadol) was added to their treatment
• Stem cell transplants used to treat certain cancers, also when tramadol was added
• Infections, when the addition of certain antibiotics led to hallucinations

Keep in mind that a number of drugs used by themselves also may cause types of visual hallucination. This is most often seen with some medications used to:

• Control hypertension, or high blood pressure
• Treat angina (chest pain), such as nitroglycerin
• Treat erectile dysfunction, such as Viagra (sildenafil)
• Manage various psychiatric and mood disorders

Alcohol or Drug Use

It may seem that hallucinations as a result of substance use are a rare occurrence, but the prevalence of alcohol and drug use in the United States remains high.

The 2019 statistics on substance abuse from the U.S. Department of Health and Human Services show that:

• Some 51% of people age 12 and up used alcohol in the previous month
• One in five people (21.1%) used tobacco in the previous month
• Nearly 36 million people (13%) used an illicit drug in the previous month

Hallucinations may occur with use of substances other than those classified as hallucinogens, such as LSD or MDMA (ecstasy). Cocaine is one example.

It's also important to remember that some people may experience hallucinations when they stop using a drug, as with alcohol withdrawal syndrome.

When to Seek Help

Hallucinations, especially the hypnagogic and hypnopompic types, are usually harmless. Still, you may want to talk to your healthcare provider about your symptoms to rule out any medical or mental health causes. That's especially true if you feel that stress or anxiety are contributing to the problem.

One way to help yourself understand your sleep patterns is to keep a journal of your symptoms, noting:

• When your hallucinations begin
• How often they occur
• How long the hallucinations last
• Any other sleep problems, such as insomnia
• Any daytime sleepiness and how often this occurs

Knowing these answers will help you to track your symptoms but also provides a way for you to give more comprehensive information when talking with your healthcare team.

Summary

It's quite common to experience brief hallucinations when you're falling asleep, called hypnagogic hallucinations. These episodes also may occur when you're waking up and are referred to as hypnopompic hallucinations.

These fleeting, visual or hearing-related hallucinations, which may seem like lucid dreams as you become consciously aware of them, aren't necessarily the sign of a medical issue.

They can, however, be a sign of a more serious condition. In some cases, hallucinations may be related to a mental health condition, but they also may be caused by a medical issue like narcolepsy or Parkinson's disease, or by prescription medications or other drugs.