Hallucinations while falling asleep are a fairly common experience — up to 70 percent of people experience it at least once. Known as hypnagogic hallucinations, they're typically brief, fleeting, and nothing to worry about.
Here are some facts on why they occur and the symptoms that aren’t normal, so you’ll know when it’s time to talk to your doctor.
What Are Hypnagogic Hallucinations?
Hypnagogic hallucinations are false experiences involving your senses that happen during the transition period between waking and sleep (hypnagogia).
Like other types of hallucinations, they may feel real, but are not. They can occur in anyone, though they’re more common in people who have certain health conditions, like
narcolepsy.
Another type of hallucination that happens in the periods between being awake and asleep is hypnopompic hallucinations. They’re similar to hypnagogic hallucinations, but happen as you’re waking up.
Neither is typically a cause for concern.
They are also not dreams. Unlike hypnagogic and hypnopompic hallucinations, which involve brief sounds or images, dreams typically follow a storyline. It’s also usually clearer when you wake up from a dream. A hypnagogic or hypnopompic hallucination can blur with reality because they occur when you’re partly awake.
But there is some controversy over whether these experiences actually qualify as “hallucinations.” By definition, hallucinations occur when someone is fully awake and alert. They also typically affect someone’s sense of self or personal narrative, whereas hypnagogic hallucinations do not.
What Do Hypnagogic Hallucinations Feel Like?
Hypnagogic hallucinations vary from person to person, but most are brief.
The most common types are:
- Visual Most hypnagogic hallucinations are visual, typically involving changing geometric patterns, shapes, or flashes of light. They can also include images, such as animals or people.
- Tactile and Kinetic Sensations Many hypnagogic hallucinations involve feelings of weightlessness, falling, or even sensing someone else in the room.
- Auditory Hypnagogic hallucinations can include sounds like people talking or animal noises.
What Causes Hypnagogic Hallucinations?
Hypnagogic hallucinations often occur in healthy people. Unlike daytime hallucinations (which can interfere with daily life and signal an underlying medical condition like schizophrenia or Parkinson’s disease), they don’t typically make someone question reality or the sense of who they are.
In other words, people don’t usually act upon or dwell on these experiences.
Women, younger adults, and those with sleep issues like
insomnia are more likely to report hypnagogic hallucinations, according to some research.
Sleep deprivation may contribute to hypnagogic hallucinations because it causes the borders between ‘wake’ and ‘sleep’ to begin to break down, says
Jamie Zeitzer, PhD, a researcher and professor of sleep medicine at Stanford University in Palo Alto, California.
“Different parts of the brain can be signaling for wake and sleep simultaneously,” Dr. Zeitzer notes.
Potential triggers for hypnagogic hallucinations may include the following factors, most of which are connected in some way to too little sleep.
Treatment and Management
If hypnagogic hallucinations aren’t causing distress or excessive daytime sleepiness, they don’t require intervention, says Jocelyn Y. Cheng, MD, the vice chair of the American Academy of Sleep Medicine public safety committee.
Even then, lifestyle changes are typically the first line of defense, Dr. Cheng says. Hypnagogic hallucinations may diminish if you get enough high-quality sleep, follow a regular
sleep schedule, and avoid alcohol. If you’re taking certain medications associated with hypnagogic hallucinations, talk to your doctor about changing your dose or switching.
Best practices for quality sleep include:
When to See a Doctor
If hypnagogic hallucinations cause anxiety or distress, or you have other symptoms (like sudden, overwhelming daytime sleepiness or muscle weakness), talk to a doctor rather than self-diagnosing.
They can review your current medications and determine if you have an underlying condition, like
narcolepsy, that may be contributing.
Also, see your doctor if you begin experiencing hallucinations during the day. This may be due to substance use, certain medications, or a temporary condition such as a high fever or urinary tract infection. Alternatively, it may indicate a neurological disorder, such as
Parkinson’s disease or
Alzheimer’s disease, or a mental health condition like
schizophrenia.
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