Parasomnias are unwanted movements, behaviors, emotions, perceptions, or other experiences that occur during sleep or during the transition into or out of sleep. Sleepwalking, sleep terrors, nightmares, REM sleep behavior disorder, sleep paralysis, and sleep-related hallucinations are different parasomnias. They do not share one cause, level of risk, test, or treatment 1.
The most useful first question is not simply, “What did the person do?” It is: When in the sleep period did it happen, how did the person respond, what do they remember, and what did a witness observe?
The main types of parasomnia
| Pattern | What it can look like | Helpful clues |
|---|---|---|
| NREM disorder of arousal | Confused behavior, sitting up, walking, screaming, eating, or sexual behavior | Incomplete awakening, reduced responsiveness, confusion, and often limited recall |
| Nightmare | A disturbing dream that causes awakening | The person becomes alert and can usually recall a dream narrative |
| REM sleep behavior disorder | Talking, shouting, punching, kicking, or other apparent dream enactment | Repeated episodes plus REM sleep without normal muscle quieting on video-polysomnography |
| Sleep paralysis or sleep-related hallucination | Awareness without the ability to move, or vivid sights, sounds, touch, or a sensed presence | Occurs while falling asleep or waking; the person may be frightened but becomes fully awake |
| Other sleep-related event | Eating, bedwetting, exploding-head sensations, or isolated sleep talking | The exact pattern and differential diagnosis matter more than the umbrella label |
This table is a starting point. Timing and recall are helpful, but neither is absolute. A person with an NREM disorder may remember part of an episode, and dream-like thoughts can occur outside REM sleep 2.
NREM disorders of arousal
Confusional arousals, sleepwalking, and sleep terrors arise from incomplete arousal out of non-rapid eye movement sleep, often deep NREM sleep. The person may have open eyes and move through the environment while remaining difficult to engage. Confusion and partial or complete amnesia are common, but memory is not a reliable all-or-nothing test 2.
A sleep terror usually involves abrupt fear, screaming, marked body activation, and poor responsiveness. It is different from a nightmare, in which the person wakes more fully and can often describe the dream. Sleepwalking can range from sitting up or handling objects to leaving the bedroom. Sleep-related eating disorder and sexsomnia can also occur as complex NREM behaviors and deserve careful assessment because of poisoning, allergy, consent, injury, and legal risks 1.
NREM disorders of arousal are especially familiar in childhood. A typical, occasional, noninjurious event in an otherwise well child often improves with development. New onset in adulthood, a major change in a longstanding pattern, repeated injury, or highly stereotyped movements needs more evaluation for another sleep disorder, seizures, medicines, substances, or neurologic illness 2.
Nightmares
A nightmare is a disturbing dream followed by awakening and recall. Occasional nightmares are not necessarily a disorder. They become a clinical concern when they recur and cause substantial distress, fear of sleep, disrupted rest, or impaired daytime functioning.
Nightmares may occur without another condition or alongside trauma, post-traumatic stress disorder, mood symptoms, medicines, substance use, or withdrawal. Dream content alone cannot identify the cause, and symbolic interpretation is not a medical diagnostic test. For recurrent nightmare disorder and PTSD-associated nightmares in adults, the AASM recommends imagery rehearsal therapy, a structured treatment that rescripts and rehearses a changed version of the nightmare while awake 3.
REM sleep behavior disorder
During typical REM sleep, most skeletal muscles become quiet. In REM sleep behavior disorder (RBD), that muscle quieting is reduced and a person has repeated sleep-related vocalizations or movements that can appear to enact a dream. The behavior may include shouting, grabbing, punching, kicking, jumping, or falling from bed.
Dream enactment by history is not enough for a definite diagnosis. RBD requires appropriate clinical features and video-polysomnography showing REM sleep without atonia, meaning excess muscle activity during REM sleep. Video and audio help determine whether the recorded movements match the sleep signals 4.
Obstructive sleep apnea, NREM parasomnias, nocturnal seizures, trauma-related nightmares, and some medicines or substances can produce or contribute to RBD-like behavior. Narcolepsy and certain neurologic conditions can also occur with RBD 5.
RBD and future neurologic disease
When RBD is confirmed and is not clearly explained by a current neurologic disorder, narcolepsy, medicine, or substance, it is called isolated RBD. In specialist cohorts, isolated RBD is strongly associated with later diagnosis of an alpha-synuclein-related disease such as Parkinson disease, dementia with Lewy bodies, or multiple system atrophy 65.
This association is important, but it is not a prediction of an individual's exact future. Cohort estimates come largely from people diagnosed in specialty centers, follow-up time differs, and RBD does not reveal which condition might develop or when. Dream movement without a confirmed RBD diagnosis should not be treated as a neurodegenerative forecast.
A person with confirmed isolated RBD can discuss the evidence and their preference for prognostic information with a sleep or neurology clinician. Follow-up may include changes in movement, thinking, smell, blood pressure regulation, and other neurologic features. Current RBD treatment is aimed at injury prevention and symptom control; it has not been shown to prevent a future neurodegenerative disease 5.
Sleep paralysis and sleep-related hallucinations
In sleep paralysis, awareness returns before REM-related muscle paralysis has fully lifted, or the paralysis begins as the person is falling asleep. The person cannot move or speak for a short period but continues breathing. A vivid image, sound, touch, pressure sensation, or sensed presence may occur at the same sleep-wake boundary. These experiences can be frightening without being supernatural or proof of a psychiatric disorder 1.
Isolated episodes can occur without another illness. Frequent sleep paralysis or sleep-related hallucinations accompanied by irresistible daytime sleepiness, sleep attacks, or emotion-triggered muscle weakness should prompt evaluation for narcolepsy 7. Hallucinations that persist in full wakefulness, occur with sudden confusion, or began during an acute illness need a different medical assessment.
Sleep-related behaviors and movements that need a closer label
Sleep talking can occur alone or with several parasomnias and does not identify a sleep stage by itself. Bedwetting and exploding head syndrome are classified separately within the broader parasomnia group. Rhythmic movement disorder, sleep-related bruxism, restless legs syndrome, and periodic limb movement disorder are sleep-related movement disorders rather than parasomnias, although a witness may simply describe all of them as “moving in sleep” 1.
Conditions that can mimic a parasomnia
Sleep-related epilepsy
Focal seizures during sleep may cause sudden sitting, vocalization, stiffening, posturing, bicycling-like movements, wandering, or other complex behavior. Compared with a typical NREM disorder of arousal, concern rises when episodes are very brief, highly similar each time, frequent in clusters, involve a consistent one-sided or unnatural posture, or occur throughout the night. These clues are not diagnostic, and a normal routine EEG does not exclude sleep-related epilepsy 28.
Breathing and movement-related arousals
Obstructive sleep apnea can cause gasping, choking, body movement, and repeated arousals. It can coexist with or help precipitate a parasomnia. Periodic limb movements can also produce recurrent arousals. Loud snoring, witnessed breathing pauses, morning headaches, or substantial daytime sleepiness should move breathing assessment higher on the list 92.
Nocturnal panic, trauma, and dissociative events
A nocturnal panic attack generally brings a person into wakefulness with intense fear and physical panic symptoms. Trauma-related nightmares are remembered dreams, while trauma-related dissociative episodes may arise during apparent wakefulness and can be more prolonged. These patterns can coexist with parasomnias, so a trauma history should guide compassionate assessment rather than an automatic explanation for every nighttime event.
Medicines, substances, and withdrawal
Prescription medicines, over-the-counter products, alcohol, cannabis, other substances, intoxication, and withdrawal can change arousal or REM sleep and may provoke or unmask nighttime behavior. A clinician should review the timing of every product and any recent changes. Do not stop or alter a prescribed medicine on your own, because withdrawal or loss of treatment can create separate risks. The AASM treats supervised discontinuation as only one possible option when drug-induced RBD is suspected 5.
Delirium and other waking confusion
Delirium is a sudden change in attention, awareness, and thinking that can fluctuate and worsen at night. Unlike a parasomnia, the confusion is not limited to a sleep event. It may reflect infection, medication effects, intoxication or withdrawal, metabolic illness, or another acute problem. Sudden confusion while awake needs immediate medical assessment 10.
What helps identify the event
A witness account is often central
The person may have little memory of an event, so a bed partner, parent, roommate, or caregiver may provide the most useful details. Record:
- when the event happened relative to falling asleep
- what happened first and how the movements unfolded
- whether each episode looks the same
- responsiveness to a calm voice and whether the eyes were open
- speech, breathing, color change, stiffening, jerking, or one-sided movement
- duration and whether events cluster
- dream recall, confusion, injury, incontinence, tongue injury, or weakness afterward
- recent illness, schedule change, missed sleep, medicines, substances, and alcohol
- snoring, breathing pauses, leg symptoms, and daytime sleepiness
A diary can show timing and frequency over several weeks. It does not need to capture an event every night to be useful.
Home video can add context, but safety comes first
A brief phone or home-camera recording can help a clinician see movement pattern, responsiveness, breathing sounds, and duration. Record from a safe distance when an event is already happening. Do not provoke an episode, block an exit, place equipment where someone can trip, or delay urgent help in order to film. Home video can strengthen the history but cannot show sleep stage, brain electrical activity, breathing physiology, or REM muscle tone 2.
Consumer watches, rings, and sleep apps cannot diagnose a parasomnia or seizure. Their proprietary stage labels are not a replacement for clinical video-polysomnography or EEG 11.
Sleep testing is selective
A classic, noninjurious childhood sleepwalking or sleep-terror history often does not require a sleep study. Video-polysomnography becomes more useful when the event is injurious, began in adulthood, is unusually frequent or stereotyped, could be RBD or epilepsy, has not responded as expected, or comes with signs of sleep apnea or periodic limb movements 89.
When seizures are part of the differential, the sleep laboratory may add an expanded EEG montage and synchronized video rather than using only the channels needed for routine sleep staging. RBD evaluation also needs adequate limb and chin muscle recording during REM sleep 84.
A single night may not capture an intermittent event. The result must still be interpreted with the witness history and any safe home video.
Reduce injury risk while the cause is assessed
Match the precautions to what has actually happened:
- clear the floor and the route around the bed
- remove weapons, sharp objects, glass, and heavy items that could be thrown
- lower the bed or place a mattress beside it if falls are possible
- pad sharp furniture corners and move furniture away from the bed
- secure accessible windows and exterior doors while preserving a safe fire exit
- keep car keys, hazardous tools, medicines, and toxic substances inaccessible
- avoid a top bunk for a child who wanders
- consider separate sleeping space when a bed partner is at risk
These measures are central to RBD care and also apply to injurious NREM behaviors 51.
During a sleepwalking or confusional episode, keep your voice calm and give the person space. If it is safe, gently guide them away from hazards and back toward bed. Waking a sleepwalker is not inherently harmful, but sudden shouting, grabbing, blocking, or physical restraint can worsen confusion and provoke defensive behavior. If immediate danger makes waking necessary, use a calm voice and the least force possible 1.
Do not punish a child or adult for behavior they did not consciously choose. Do not use restraints, improvised barriers that could trap someone in a fire, or a forced-awakening routine without professional guidance.
Treatment depends on the diagnosis
There is no single parasomnia treatment plan. A clinician first addresses documented contributors such as insufficient sleep opportunity, sleep apnea, periodic limb movements, a medicine effect, substance use, trauma, or another medical condition.
For NREM disorders, education and environmental safety may be enough when episodes are infrequent and noninjurious. Predictably timed childhood episodes may sometimes be managed with clinician-guided scheduled awakenings. Evidence for behavioral and medication treatments in adults remains limited, so risk, frequency, and the competing diagnosis should guide the plan 2.
Recurrent nightmares may respond to nightmare-focused treatment such as imagery rehearsal therapy, with trauma treatment added when appropriate 3. Isolated sleep paralysis often needs explanation and attention to a stable, adequate sleep opportunity, while frequent episodes with daytime sleepiness need a narcolepsy assessment.
For confirmed RBD, the AASM places bedroom safety first and provides conditional medication options chosen according to age, fall risk, cognition, sleep apnea, other conditions, and patient preference. These medicines can cause adverse effects and should not be started or adjusted without the treating clinician 5.
When to seek care
Arrange a clinical or sleep-specialist assessment when an event:
- starts for the first time in adulthood or changes substantially
- causes injury, leaves the home, involves driving, weapons, fire, or unsafe eating
- is frequent, highly repetitive, or stereotyped
- includes dream enactment, especially punching, kicking, or falling from bed
- comes with breathing pauses, gasping, marked daytime sleepiness, or emotion-triggered weakness
- causes major distress, fear of sleep, or impaired daytime function
Seek urgent help for a serious injury, difficulty breathing, blue or gray color, failure to wake normally after an event, or sudden new neurologic symptoms. Treat a first suspected seizure as a medical event, not a presumed parasomnia.
If a convulsive event lasts more than five minutes, another begins before recovery, breathing or waking is difficult afterward, or the person is injured, call emergency services. Do not hold the person down or put anything in their mouth 12.
Sudden confusion that continues while the person is awake, especially with fever, illness, medication change, intoxication, withdrawal, weakness, or speech trouble, also needs immediate medical assessment 10.
Common questions
Is it dangerous to wake a sleepwalker?
Waking does not cause medical harm, but a sudden or forceful awakening can cause fear, confusion, or defensive movement. Calmly guide the person away from danger when possible. Wake gently if that is necessary to prevent immediate injury.
How can I tell a nightmare from a sleep terror?
After a nightmare, the person usually wakes, becomes oriented, and can describe the dream. During a sleep terror, the person may scream or look terrified while remaining difficult to engage, then have limited recall. Timing can help, but the behavior and recall are more useful than assuming every early event is a terror or every late event is a nightmare.
Does acting out a dream always mean RBD?
No. Nightmares, NREM disorders, sleep apnea, seizures, trauma-related events, and medicines can resemble dream enactment. A definite RBD diagnosis requires the right clinical history plus video-polysomnographic evidence of REM sleep without atonia.
Does a child need a sleep study for sleepwalking?
Not usually when the episodes are typical, occasional, noninjurious, and the child is otherwise well. A study becomes more useful when events are atypical or dangerous, when seizures are possible, or when snoring, breathing pauses, unusual leg movements, or major daytime sleepiness suggest another sleep disorder.
