Sleep-related hallucinations are vivid, often intense visual or sensory experiences that occur while falling asleep or waking up. They can involve realistic images of stationary objects, sensations of movement (like falling or running) or the feeling that someone else is in the room. These hallucinations are considered parasomnias, a type of sleep disorder involving unwanted actions or experiences during sleep, the transition between sleep stages, or the transition between sleep and wakefulness.
How Common are Sleep-Related Hallucinations?
Nearly 40 percent of adults experience sleep-related hallucinations, which are rare in children. They occur equally in men and women. Sleep-related hallucinations often occur with other sleep disorders, including narcolepsy and sleep paralysis.
Symptoms of Sleep-Related Hallucinations
Sleep-related hallucinations are parasomnias associated with:
Excessive daytime sleepiness
Sleep-related hallucinations are dream-like, but they differ from real dreams. Dreams occur during REM sleep, and the person is considered to be completely asleep. During a hallucination, the person is considered awake.
Types of Sleep-Related Hallucinations
Hypnagogic hallucinations are sleep-related hallucinations that occur while falling asleep. These hallucinations can be visual or tactile and include the perception of sights or sounds that aren’t actually there. The most common type of sleep-related hallucination, hypnagogic hallucinations are more than twice as common as hypnopompic hallucinations. They are a symptom of narcolepsy, although patients without narcolepsy can experience these hallucinations. Researchers believe that most adults will experience a hypnagogic hallucination at least once in their lifetime.
Hypnopompic hallucinations occur during the transition from sleep to wakefulness, i.e. when waking up. Like hypnagogic hallucinations, these episodes are brief and can include sights, sounds, and sensations that are not there. Hypnopompic hallucinations occur less frequently than hypnagogic hallucinations, with a lifetime prevalence between 6 and 13 percent.
What Causes Sleep-Related Hallucinations?
Sleep-related hallucinations were once associated with mental illness, but researchers now know that these hallucinations can occur without any mental illness. However, people with anxiety, depression or bipolar disorder are twice as likely to experience sleep-related hallucinations.
Stress, sleep deprivation, insomnia, and alcohol use and certain medications make sleep-related hallucinations more likely.
Like narcolepsy, the risk of sleep-related hallucinations may be inherited.
People taking tricyclic antidepressants may be more likely to experience sleep-related hallucinations. Injuries to the brain may increase the risk of sleep-related hallucinations. Finally, people taking hallucinogenic drugs like LSD may experience hallucinations related to sleep.
Because sleep-related hallucinations are sometimes linked to other sleep disorders, a sleep specialist will evaluate a patient’s health history and sleep patterns to determine if another disorder is present. A specialist may request a polysomnogram, an overnight sleep study that measures brain, heart and lung activity, to look for fragmented sleep patterns that might indicate an underlying disorder. In some cases, a doctor may request an MRI of the brain.
Treatment for sleep-related hallucinations varies depending on their cause. When sleep-related hallucinations are brought on by using alcohol, drugs, or medications, discontinuing those substances may end the hallucations. Treating underlying sleep disorders like narcolepsy or insomnia can help resolve unwanted hallucinations. Avoiding stress and sleep deprivation is also recommended.