Types of Parasomnias

What is sleepwalking? 

Sleepwalking involves getting out of bed or performing other behaviours while a person is still partly asleep. It is considered a disorder of arousal because the brain has not completed the transition from NREM sleep to full wakefulness. 

Despite the name, sleepwalking may involve more than walking. A person may sit up, move around the room, get dressed, move objects, eat, or perform other familiar behaviours. 

The person may have their eyes open and appear awake, but their awareness and judgment remain impaired. 

What might it look like? 

During an episode, a person may: 

• Sit up or leave the bed 

• Walk around with a blank or distant expression 

• Respond slowly or not respond normally 

• Perform routine or inappropriate behaviours 

• Appear confused 

• Become agitated if abruptly awakened 

• Return to bed without fully awakening 

• Have little or no memory of the event the following day 

Episodes vary in complexity. Some are brief and uncomplicated, while others may involve potentially dangerous activities. 

Who can experience it? 

Sleepwalking is commonly associated with childhood, but it can persist or occur in adults. The supplied reviews describe family patterns, suggesting that some people may have an inherited susceptibility. 

Adult sleepwalking may deserve additional evaluation, particularly when it is new, frequent, dangerous, or associated with other symptoms. 

Possible contributing factors 

Factors discussed in the supplied articles include: 

• Sleep deprivation 

• Irregular or disrupted sleep 

• Noise or repeated awakenings 

• Other sleep conditions that fragment sleep 

• Certain medications, particularly medications that affect awareness or memory 

• Alcohol or other substances 

• Stress 

• Familial susceptibility 

These factors do not affect everyone in the same way. 

Is sleepwalking dangerous? 

Many episodes are uncomplicated, but reduced awareness can create a risk of: 

• Falls 

• Collisions with furniture 

• Injuries involving stairs or windows 

• Leaving the bedroom or home 

• Handling unsafe objects 

• Performing complex activities without normal judgment 

Safety becomes especially important when episodes involve leaving the bed. 

When should I seek medical advice? 

Consider speaking with a healthcare professional when sleepwalking: 

• Causes or risks injury 

• Involves leaving the home 

• Begins unexpectedly in adulthood 

• Becomes more frequent or complex 

• Significantly disrupts sleep 

• Occurs with breathing problems, severe daytime sleepiness, or other concerning symptoms 

• May be connected to medication or substance use 

Do not stop a prescribed medication without consulting a physician or pharmacist. 

Frequently asked question: Should I wake a sleepwalker? 

Avoid startling, shouting at, or physically confronting the person. When possible, calmly guide them away from danger and back toward bed. 

If the person must be awakened for immediate safety, use a calm voice and gentle approach. They may initially be confused, frightened, or agitated. 

Primary supplied sources: Irfan et al. (2021); Kazi (2022); Mayo Clinic (2017); Zergham (2023).  

What is sleep talking? 

Sleep talking involves speaking or making vocal sounds during sleep. It is also called somniloquy. 

Speech may consist of a few unclear sounds, complete words, short phrases, or longer statements. The volume and emotional tone can vary. 

Sleep talking can occur on its own or alongside another sleep-related condition. 

What might it sound like? 

A person may: 

• Mum­ble or make unclear sounds 

• Say individual words 

• Speak in full sentences 

• Whisper, shout, laugh, or cry 

• Appear to respond to someone who is not awake 

• Have no memory of speaking afterward 

The content of sleep speech is not necessarily connected to a dream, waking thoughts, or personal beliefs. 

Who can experience it? 

Sleep talking can occur in both children and adults. An occasional episode may not indicate a health problem. 

Because the person is asleep, they often learn about it from a parent, partner, roommate, or recording. 

Possible contributing factors 

The supplied patient-oriented articles discuss possible associations with: 

• Sleep deprivation 

• Stress 

• Fever or illness 

• Alcohol 

• Certain medications 

• Other sleep conditions 

• Disrupted or poor-quality sleep 

A single episode does not establish that any particular factor is responsible. 

Is sleep talking dangerous? 

Sleep talking itself is generally not physically dangerous. However, frequent or intense vocalization may disturb the sleep of the speaker or other people. 

Vocalization accompanied by forceful movements, leaving the bed, breathing problems, or significant fear may require a broader sleep assessment. 

When should I seek medical advice? 

Consider seeking advice when sleep talking: 

• Begins suddenly or changes substantially 

• Occurs very frequently 

• Seriously disrupts sleep 

• Includes screaming, violent movements, or leaving the bed 

• Occurs with other concerning nighttime behaviours 

• Causes significant distress 

Frequently asked question: Does sleep talking reveal someone’s true thoughts? 

Sleep speech may be fragmented, unclear, or unrelated to the person’s waking beliefs. It should not be treated as an intentional or reliable statement. 

Primary supplied sources: Cleveland Clinic (2021); Miller (2023); Suni (2023); Irfan et al. (2021). 

What are sleep terrors? 

Sleep terrors are episodes of intense fear that arise from NREM sleep. They are sometimes called night terrors. 

During an episode, the person may appear terrified without being fully awake or aware of their surroundings. 

Sleep terrors are different from nightmares. 

What might an episode look like? 

A person may: 

• Suddenly scream or cry 

• Sit up in bed 

• Appear extremely frightened 

• Breathe quickly 

• Have a rapid heartbeat 

• Sweat 

• Move forcefully 

• Be difficult to comfort 

• Respond poorly to questions 

• Have little or no memory afterward 

Attempts to abruptly wake or stop the episode may increase confusion or agitation. 

Who can experience them? 

Sleep terrors are especially associated with childhood, but adults can also experience them. 

In children, episodes may decrease with development. However, safety risks, frequent episodes, major sleep disruption, or substantial family distress can still justify professional advice. 

Possible contributing factors 

Factors discussed in the supplied NREM parasomnia literature include: 

• Sleep deprivation 

• Irregular or disrupted sleep 

• Noise 

• Illness 

• Stress 

• Certain medications 

• Other conditions that fragment sleep 

• Familial susceptibility 

Sleep terror or nightmare? 

During a sleep terror, the person may appear terrified but remain partly asleep, be difficult to comfort, and remember little afterward. 

After a nightmare, the person generally becomes alert and can remember the distressing dream. 

Are sleep terrors dangerous? 

The fear displayed during an episode can be alarming, but the main physical concern is injury from sudden or forceful movement or associated sleepwalking. 

The sleep environment should be reviewed when there is a risk of falling, leaving the bed, or striking nearby objects. 

When should I seek medical advice? 

Consider professional advice when episodes: 

• Cause or risk injury 

• Are frequent or worsening 

• Regularly disrupt sleep 

• Continue to cause substantial problems 

• Begin unexpectedly in adulthood 

• Occur with other concerning sleep symptoms 

• Significantly affect the person or family 

Primary supplied sources: Irfan et al. (2021); Ntafouli et al. 

What is nightmare disorder? 

Nightmares are vivid, distressing dreams. An occasional nightmare does not necessarily indicate a disorder. 

Nightmare disorder involves repeated, distressing, well-remembered dreams that cause meaningful sleep disruption, daytime distress, or impairment. 

The dreams often involve threats to safety, survival, or physical integrity. 

What might someone experience? 

A person may: 

• Awaken from a frightening or distressing dream 

• Become alert quickly 

• Clearly remember the dream 

• Feel afraid to return to sleep 

• Avoid bedtime 

• Experience daytime anxiety or distress 

• Have fatigue or low energy 

• Have difficulty concentrating 

• Experience effects on school, work, relationships, or family functioning 

Who can experience it? 

Nightmares occur in children and adults. Nightmare disorder is also reported in people experiencing trauma-related and psychiatric conditions, although it can occur without them. 

Having nightmares does not automatically mean that a person has a psychiatric disorder. 

Possible contributing factors 

The supplied review discusses possible associations with: 

• Trauma 

• Post-traumatic stress 

• Increased emotional arousal 

• Difficulty processing or reducing learned fear 

• Certain medications 

• Alcohol withdrawal 

• Other sleep conditions 

• Psychiatric conditions 

Different factors may apply to different people. 

Nightmare disorder or sleep terror? 

A person awakening from a nightmare generally becomes alert and can describe the dream. 

During a sleep terror, the person may display intense fear while remaining partly asleep and may remember little the next day. 

Is nightmare disorder dangerous? 

Nightmares do not usually produce the same environmental injury risks as sleepwalking or dream enactment. However, repeated nightmares can substantially affect: 

• Sleep quality 

• Willingness to sleep 

• Mood 

• Concentration 

• Energy 

• Daily functioning 

• Family or caregiver sleep 

The supplied review also discusses an association between nightmares and psychological distress. Serious emotional distress should be discussed with a qualified professional. 

When should I seek medical advice? 

Consider seeking help when nightmares: 

• Occur repeatedly 

• Cause fear of sleeping 

• Produce significant daytime distress 

• Affect school, work, relationships, or concentration 

• Are associated with trauma 

• Begin after a medication or substance change 

• Occur with dream enactment or other unusual sleep symptoms 

Can nightmare disorder be treated? 

The supplied review identifies imagery rehearsal therapy as an important non-medication treatment. It involves changing the storyline or ending of a recurring nightmare and rehearsing the revised version while awake. 

Treatment should be selected according to the person’s symptoms, history, and whether the nightmares are associated with trauma or another condition. 

Primary supplied source: Stefani and Högl (2021). 

What is sleep paralysis? 

Sleep paralysis is a temporary inability to move that occurs while falling asleep or waking. 

During REM sleep, muscle activity is normally reduced. Sleep paralysis occurs when this REM-related muscle immobility continues briefly while awareness has returned. 

An isolated episode does not necessarily indicate a disorder. Recurrent isolated sleep paralysis involves repeated episodes that cause significant fear or distress. 

What might it feel like? 

During an episode, a person may: 

• Be aware of their surroundings 

• Be unable to move their arms, legs, or body 

• Be unable to speak normally 

• Feel pressure on the chest 

• Feel that breathing requires more effort 

• Sense a presence in the room 

• See, hear, or feel vivid things 

• Experience intense fear 

• Regain movement suddenly 

The experience can feel very real and frightening. 

Who can experience it? 

An isolated episode can occur in otherwise healthy people. Recurrent episodes are less common. 

The supplied articles discuss possible associations with disrupted sleep, irregular schedules, and other sleep or mental-health conditions. 

Possible contributing factors 

Factors identified in the supplied reviews include: 

• Sleep deprivation 

• Irregular sleep–wake schedules 

• Jet lag 

• Poor or disrupted sleep 

• Stress 

• Sleeping position 

• Other sleep conditions 

These factors do not explain every episode. 

Is sleep paralysis dangerous? 

An episode can be extremely frightening, but it is temporary. The unusual perceptions that sometimes occur are connected to the transition between REM sleep and wakefulness. 

Repeated episodes can still affect sleep, increase bedtime anxiety, and cause substantial distress. 

What can I do during an episode? 

Information from the supplied clinical review suggests that understanding the experience may reduce fear. Some people find it helpful to: 

• Remind themselves that the episode is temporary 

• Focus on calm breathing 

• Try to move a small part of the body 

• Focus attention on a familiar sound or object 

• Discuss repeated episodes with a healthcare professional 

These strategies should not be presented as guaranteed to end every episode. 

When should I seek medical advice? 

Consider seeking advice when sleep paralysis: 

• Happens repeatedly 

• Causes intense or ongoing fear 

• Makes you avoid sleep 

• Is associated with severe daytime sleepiness 

• Occurs with other unusual sleep symptoms 

• Significantly affects daily life 

Primary supplied sources: Sharpless (2016); Stefani and Högl (2021); Cleveland Clinic (2021). 

What is REM sleep behaviour disorder? 

During typical REM sleep, most skeletal muscles remain temporarily inactive. REM sleep behaviour disorder—often abbreviated as RBD—occurs when this normal reduction in muscle activity is impaired. 

A person may vocalize or physically act in ways that correspond with a dream. 

RBD cannot be confirmed by dream enactment alone. The supplied reviews describe overnight video-polysomnography as important for establishing a definite diagnosis and excluding other explanations. 

What might an episode look like? 

A person may: 

• Talk, shout, laugh, or cry 

• Make defensive movements 

• Punch or kick 

• Reach or grab 

• Sit up suddenly 

• Jump or fall from bed 

• Injure themselves or a bed partner 

• Recall an action-filled or threatening dream after awakening 

When awakened, the person may become alert relatively quickly and describe the dream. 

Who can experience it? 

The supplied reviews discuss RBD most often in middle-aged and older adults, although it can occur in younger people and in association with certain medications, narcolepsy, or neurological conditions. 

Age alone cannot confirm or exclude RBD. 

Possible contributing or associated factors 

The supplied articles discuss associations with: 

• Certain neurological conditions 

• Narcolepsy 

• Some medications, including certain antidepressants 

• Brain injury or other neurological changes 

• Dream-enacting behaviour without an identified associated condition 

An association does not mean that every person with dream enactment has or will develop a neurological disorder. 

Is RBD dangerous? 

RBD can create a significant risk of injury because movements may be sudden or forceful. 

Potential injuries include: 

• Falling from bed 

• Striking furniture 

• Cuts or bruises 

• Injuries to a bed partner 

Environmental safety is therefore an important part of management. 

When should I seek medical advice? 

Repeated dream enactment should be discussed with a healthcare professional, particularly when it involves: 

• Punching or kicking 

• Falling or jumping from bed 

• Injury 

• Risk to a bed partner 

• Increasing frequency or intensity 

• New neurological symptoms 

• A possible connection with medication 

How is it assessed? 

Assessment may include: 

• A detailed description of the events 

• Information from a bed partner 

• Medication and health history 

• Neurological evaluation 

• Overnight video-polysomnography 

Recordings made safely at home may sometimes help demonstrate what was observed, but recording should never take priority over safety or privacy. 

Can RBD be treated? 

The supplied reviews discuss: 

• Making the sleep environment safer 

• Reviewing possible contributing medications or conditions 

• Melatonin 

• Clonazepam 

• Ongoing clinical follow-up 

Medication decisions require individualized medical assessment because benefits and risks vary. 

Primary supplied sources: Dauvilliers et al. (2018); Jung (2016); Pacheco (2023); Roguski et al. (2020). 

What are confusional arousals? 

Confusional arousals occur when a person partly awakens from NREM sleep but remains disoriented. 

The person may appear awake enough to speak or move while their awareness, reasoning, and memory remain impaired. 

What might an episode look like? 

A person may: 

• Sit up in bed 

• Look confused 

• Stare 

• Speak slowly or unclearly 

• Give inappropriate or unusual answers 

• Fail to recognize their surroundings immediately 

• Resist attempts to interact 

• Become agitated 

• Return to sleep 

• Remember little or nothing afterward 

The supplied review notes that episodes are often brief but may sometimes last longer. 

Who can experience them? 

Confusional arousals can occur in children and adults. They are grouped with sleepwalking and sleep terrors because the conditions share features associated with incomplete awakening from NREM sleep. 

Possible contributing factors 

Factors discussed in the supplied review include: 

• Sleep deprivation 

• Interrupted or fragmented sleep 

• Noise 

• Circadian disruption 

• Sedating medications 

• Other sleep conditions 

• Familial susceptibility 

How are they different from sleepwalking? 

The main feature of a confusional arousal is disorientation during partial awakening. The person commonly remains in bed. 

Sleepwalking includes leaving the bed or performing more complex behaviours while awareness remains impaired. 

How are they different from sleep terrors? 

Sleep terrors typically include intense fear, screaming, and strong physical activation. 

Confusional arousals mainly involve disorientation and impaired responsiveness without the same prominent display of fear. 

Are confusional arousals dangerous? 

Many episodes are uncomplicated. However, agitation, aggression, or movement can occasionally create safety concerns. 

When should I seek medical advice? 

Consider seeking advice when episodes: 

• Cause or risk injury 

• Include aggressive behaviour 

• Occur frequently 

• Significantly disrupt sleep 

• Begin unexpectedly or change substantially 

• Occur with other concerning symptoms 

• May be related to medication 

Primary supplied source: Irfan et al. (2021). 

What is sleep-related bruxism? 

Sleep-related bruxism involves repetitive jaw-muscle activity during sleep. It may include: 

• Grinding the teeth 

• Clenching the jaw 

• Bracing the jaw 

• Thrusting the lower jaw 

Sleep bruxism is different from awake bruxism, although a person may experience both. 

What might someone notice? 

Possible signs include: 

• Grinding sounds reported by another person 

• Tooth wear or damage 

• Jaw-muscle discomfort 

• Jaw fatigue 

• Morning headaches 

• Tooth sensitivity 

• Discomfort when chewing 

• Damage to dental restorations 

Symptoms do not always reflect how frequently the jaw-muscle activity occurs. Someone may have frequent activity without pain, while another person may experience symptoms with fewer recorded episodes. 

Who can experience it? 

Sleep-related bruxism can occur in children and adults. The Guaita and Högl review reports that its frequency appears to decrease with age in adults. 

Possible contributing factors 

The supplied articles discuss possible associations with: 

• Sleep arousals 

• Stress sensitivity 

• Alcohol 

• Caffeine 

• Smoking 

• Certain medications 

• Other sleep conditions 

• Neurological or psychiatric conditions in secondary cases 

These associations do not prove the cause in an individual case. 

Is sleep-related bruxism dangerous? 

It is not usually an immediate emergency, but persistent bruxism may contribute to: 

• Tooth wear 

• Damage to teeth or restorations 

• Jaw pain 

• Muscle fatigue 

• Headaches 

• Difficulty with oral functions in severe cases 

How is it assessed? 

Assessment may involve: 

• Symptoms reported by the person 

• Grinding reported by a partner or family member 

• Dental examination 

• Review of medications and health conditions 

• Sleep assessment in selected cases 

The supplied review notes that polysomnography is generally needed only in selected cases, particularly when another sleep condition is suspected. 

Can it be treated? 

The supplied review discusses: 

• Education and counselling 

• Sleep-habit changes 

• Relaxation approaches 

• Occlusal splints 

• Selected dental approaches 

• Medication in particular clinical circumstances 

• Management of an underlying condition when bruxism is secondary 

Occlusal splints may help protect the teeth and reduce grinding sounds. Their effects on the underlying sleep-related jaw activity may be temporary. 

The evidence supporting many bruxism treatments remains limited. Treatment should focus on the person’s symptoms, dental health, contributing factors, and possible coexisting conditions. 

When should I seek professional advice? 

Consider speaking with a dentist or healthcare professional when there is: 

• Tooth wear or damage 

• Jaw pain or persistent muscle fatigue 

• Morning headaches 

• Difficulty chewing 

• Broken restorations 

• Significant sleep disruption 

• Concern that medication or another condition may be contributing 

Do not purchase or use a dental device as a substitute for appropriate dental assessment. 

Primary supplied sources: Guaita and Högl (2016); Suni (2023); Ucar et al. (2022).