Parasomnias – From the Sleep Disorder Book
Sleep is a vital physiological process with important restorative functions. Parasomnias are
characterized by undesirable physical or verbal behaviors, such as walking or talking during
sleep and occur in association with sleep, specific stages of sleep or sleep-wake transitions.
The category of parasomnias comprises some of the most exceptional behavior disorders
because complex and apparently purposeful, goal-directed behavior is associated with a
deep sleeping brain. Parasomnias occur during REM sleep, any of the four stages of non-
REM sleep, and during transitions between sleep and wakefulness. Sleepwalking, sleep
terrors, and confusional arousals are associated with non-REM sleep, nightmares and sleep
paralysis are associated with REM sleep, while sleep starts and sleep talking are associated
with sleep-wake transitions. Sleep enuresis has been observed with all sleep types.
The International Classification of Sleep Disorders subdivides parasomnias into the
following four groups (Table 1): Arousal disorders, sleep-wake transition disorders, rapid
eye movement (REM) stage sleep parasomnias, and other parasomnias (American academy
of Sleep Medicine, 2004).
F. Gokben Hizli and Nevzat Tarhan
Edited by Chris Idzikowski, ISBN 978-953-51-0293-9, 202 pages, Publisher: InTech, Chapters published March 14, 2012 under CC BY 3.0 license
When accompanied with excessive motor activity and other complex motor behaviors, these
parasomnias may significantly affect the patient’s quality of life and that of the bed partner.
Motor behaviors may or may not be restricted to bed but can become dangerous when the
subject ambulates or is agitated. The behaviors are inappropriate for the time of occurrence
but may seem purposeful or goal directed. Therefore, appropriate diagnostic and
therapeutic strategies are needed (Young, 2008).
2. Causes of parasomnias
Parasomnias occur due to abnormal transitions between the three primary states of being
wake, rapid eye movement (REM) sleep, and non rapid eye movement (NREM) sleep. These
different states may overlap or intrude into one another, and it is the overlap of wakefulness
and NREM sleep that gives rise to confusional arousals, and the intrusion of REM sleep into
waking that produces REM sleep behavior disorder (Matwiyoff et al, 2010).
Parasomnias may have genetic basis, but occurrence is usually triggered by heavy physical
activity, febrile illness, sleep deprivation, excessive caffeine drinks, hypnotics, and
emotional stress. Intake of alcohol increased occurrence of confusional arousal, night terror,
and sleepwalking, while heavy intake of caffeinated drink increased occurrence of sleep
walking in a population study (Oluwole, 2010).
Sleep-wake transition disorders
Rhythmic movement disorder
Nocturnal leg cramps
Parasomnias usually associated with REM sleep
Impaired sleep-related penile erections
Sleep-related painful erections
REM sleep sinus arrest
REM sleep behavior disorder
Sleep-related abnormal swallowing syndrome
Nocturnal paroxysmal dystonia
Sudden unexplained nocturnal death syndrome
Infant sleep apnea
Congenital central hypoventilation syndrome
Sudden infant death syndrome
Benign neonatal sleep myoclonus
Table 1. The International Classification of Sleep Disorders classification of parasomnias
Heredity was described for many forms of parasomnias but detailed genetic studies are
lacking. The composition of non-REM and REM sleep was shown to have genetic roots.
Especially the amount of slow-wave sleep was recently shown to be genetically predisposed
by a specific gene, the retinoid acid receptor beta encoding gene (Young, 2008; Maret et al.,
3. Diagnosis of parasomnias
All parasomnias more commonly affect persons who have breathing disorders during sleep.
Polysomnography is appropriate for any patient with symptoms or signs of obstructive
sleep apnea, such as daytime hypersomnolence, nocturnal hypoxia, loud snoring and
increased neck circumference. REM behavior disorder often occurs concomitantly with
degenerative neurologic illnesses that may require further evaluation. In adults, the onset of
arousal disorders such as somnambulism and night terrors may reflect underlying
neurologic disease. Thus, neurologic evaluation, including imaging of the central nervous
system, may be indicated (Bornemann et al., 2006).
Diagnosis of parasomnias relies on a comprehensive clinical evaluation. Additional testing
with polysomnogram and time-synchronized video recording may be indicated for cases
that are associated with very frequent episodes, complaints of excessive sleepiness, unusual
presentation, or injury to the individual or bed partner. A formal laboratory sleep study or
polysomnogram with an expanded electroencephalographic montage can help distinguish
among non-REM and REM parasomnias and nocturnal seizures. The latter may manifest
clinically as arousals from sleep associated with vocalization and/or complex behaviors
(Farid et al., 2004).
Generally parasomnias, particularly those that are associated with non-REM sleep are
commoner in childhood, but studies showed that non- REM parasomnias are not
uncommon in adults. Parasomnias have been reported in approximately 4% of the adult
population (Ohayon et al., 2000).
Prevalence of sleepwalking, which consists of a series of complex behaviors that are
initiated during slow wave sleep and result in walking during sleep, varies from 10 per
1,000 to 145 per 1,000. In a population of adults prevalence of sleep walking was 20 per 1,000
(Guilleminault et al., 2003).
Sleep terrors, which are characterized by sudden arousal from slow wave sleep with a
piercing scream or cry, accompanied by autonomic and behavioral manifestations of intense
fear, are a common parasomnia in childhood. Its prevalence in children varies from 30% to
398 per 1,000, but prevalence of 22 per 1,000 was found in an adult population (Kales et al.,
Nightmares are frightening dreams that usually awaken the sleeper from REM sleep.
Between 10 and 20% of children experience nightmares that disturb their parents while
50% of adults have occasional nightmares and 1% have one or more nightmares per
Sleep paralysis consists of a period of inability to perform voluntary movements at sleep
onset, hypnagogic or predormital form, or upon awakening, either during the night or in the
morning, hypnopompic or postdormital. Lifetime prevalence of isolated sleep paralysis in
the general population in Germany and Italy was shown to be 62 per 1,000.
Sleep enuresis is characterized by recurrent involuntary micturition that occurs during
sleep. In children prevalence of sleep enuresis could be up to 250 per 1,000. In adults
prevalence of nocturnal enuresis varies from 2 to 38 per 1,000.
Sleepwalking occurs more frequently in children with an estimated prevalence of up to 40
per cent in this age group. Prevalence among adults is about 4 per cent.
Prevalence of RBD is estimated to be about 0.5 per cent13. REM sleep behavior disorder
tends to affect older adults, with a mean age of onset of 50 to 60 years, predominantly
5. Clinical features and symptoms
The disorders that are primarily discussed in this chapter are confusional arousals, sleep
terror disorder, sleepwalking disorder, nightmare disorder and REM sleep behavior
5.1 Confusional arousals
Arousal disorders, including sleepwalking, sleep terrors, and confusional arousals, are the
most common forms of parasomnias. They are predominantly associated with arousals from
slow-wave sleep, which in turn occur most prominently in the first third of the night. They can
present as one disorder or any combination of the three forms mentioned. Awakening the
person during the arousal type of parasomnia is difficult; the affected individual usually will
not remember the event on awakening in morning. Confusional arousals can occur throughout
the night but are seen most commonly during the first half of the major sleep period when
NREM density is highest. Confusional arousals are estimated to affect 4 percent of adults. It is
characterized by abrupt awakenings with apparent confusion, diminished vigilance,
disorientation and occasional violent or inappropriate behavior (Farid et al, 2004).
Confusional arousal typically appears in young children up to the age of five years.
Polysomnographic recordings of affected individual show clear association of confusional
arousal episodes with slow-wave sleep mainly in the first part of the night. Confusional
arousals usually are not harmful to the patient and are usually self-limited. Usually, there is
no indication to intervene during the episodes of confusional arousal (Young, 2008).
5.2 Sleep terror
Sleep terror (pavor nocturnus) is an abrupt, terrifying arousal from sleep, usually in
preadolescent boys although it may occur in adults as well. It is distinct from sleep panic
attacks. These emerge when normal wake and NREM state boundaries become destabilized
and elements of the waking state intrude into NREM sleep. Sleep terrors are believed to be a
reaction to a frightening image that results in agitated arousal and sympathetic nervous
activation. Polysomnographic recordings of these events have shown that they are
associated with 2 abnormalities during the first sleep cycle: abnormally low
electroencephalogram (EEG) power and frequent, brief, nonbehavioral EEG-defined
Symptoms are fear, sweating, tachycardia, and confusion for several minutes, with amnesia
for the event. Demystification of these conditions and reassurance, particularly for parents
of pediatric patients, is an important aspect of clinical intervention. Patients rarely
remember the events in detail, but if actively probed after 4 years of age, they often report
vague memories of having to act—run away, escape, or defend themselves—against
monsters, animals, snakes, spiders, ants, intruders, or other threats. Children may report
feeling complete isolation and fear. Parents often describe terrified facial expressions,
mumbling, shouting, and inability to be consoled.
Among arousal parasomnias, sleepwalking (somnambulism) is the most common.
Sleepwalking (somnambulism) includes ambulation or other intricate behaviors while still
asleep, with amnesia for the event. Sleepwalking is a complex behavior that ranges from
limited and noninjurious activities to dangerous activities associated with injuries to self
or others. Up to 40% of normal children have experienced at least one episode of
sleepwalking and 2% to 3% of children experience it at least once a month (Klackenberg,
It affects mostly children aged 6-12 years, and episodes occur during stage 3 or stage 4 sleep
in the first third of the night and in REM sleep in the later sleep hours. Despite widespread
prevalence of these disorders and the recognition that they may arise from incomplete
arousal, their pathophysiology is not well understood. Evidence for a strong genetic
background of sleepwalking was shown in epidemiological surveys as in twin studies.
Further evidence for heredity of sleepwalking is documented by the 10-fold increased
prevalence of sleepwalking in relatives of patients suffering from sleepwalking.
Sleepwalking in elderly people may be a feature of dementia. Idiosyncratic reactions to
drugs (eg, marijuana, alcohol) and medical conditions (eg, partial complex seizures) may be
causative factors in adults. During an episode of sleepwalking, a person may appear
agitated or calm and behavior may range from simple ambulation with a “glassy stare” to
more complex activities such as driving. Sleepwalking may be preceded by confusional
arousals or sleep terrors.
Depending on the degree of confusion, bedroom location, furniture, and strength of the
subject, sleepwalking may lead to accidents and self-injury. Safety precautions should be
taken for sleepwalking. These include removing dangerous objects, placing heavy drapes on
glass doors and windows, and special locks on doors. Sleepwalking episodes occur in slowwave
sleep, during which time the individual is not easily arousable. Family members may
gently guide the person back to the bed; strong stimuli to awaken the patient may cause
resistance or aggression and are not recommended. Sleep terror and sleepwalking episodes
are disturbing to parents but prepubertal sleepwalking is usually self-limited. Adult-onset
sleepwalking with complicated patterns of sleepwalking, however, may contain a
psychiatric component. These patients may benefit from psychotherapy, relaxation, or
hypnosis (Farid et al, 2004).
Nightmares are vivid nocturnal events that cause feelings of fear and terror, with or without
feeling anxiety. In most cases, a person having a nightmare will be abruptly awakened from
REM sleep and is able to give a detailed account of what he dreamt about. Also, the person
having a nightmare has difficulty returning to sleep. Episodes typically occur in the latter
half of the night. Following the awakening, the individual becomes fully alert and
profoundly anxious. There is vivid recall of the preceding dream as well as difficulty
returning to sleep. Compared to sleep terrors, there is less autonomic activation, and
tachycardia and tachypnea, if present, are not as severe. Episodes can be precipitated by
illness, traumatic experiences, and alcohol and medication use, such as antidepressants and
beta-antagonist antihypertensive agents.
Nightmares affect 20 to 39 percent of children between five and 12 years of age. Contrary to
popular belief, frequent nightmares in children do not suggest underlying psychopathology.
Nightmares and night terrors in children are usually disturbing to parents and family
members; therefore, proper diagnosis and education of family members are important
components of management. It is essential to control the environment by removing
dangerous objects and providing barriers to prevent escape from a safe sleeping
environment. Reassurance and support are often the only therapy required because these
disorders rarely, if ever, reflect underlying illness and usually disappear with maturity.
Pharmacologic intervention is not usually indicated; in fact, it should be discouraged
because it may contribute to further sleep disruption. Behavioral methods for treatment of
frequent nightmares are effective in older children.
5.5 Rapid Eye Movement (REM) sleep behavior disorder
REM sleep is characterized by a paucity of muscle activity with near complete somatic
muscular atonia. REM sleep behavior disorder is characterized by the intermittent loss of
REM atonia due to disinhibition of normally inhibitory mid-brain projections to spinal
motor neurons. This, in conjunction with an active dream state, results in behavioral
release and the apparent “acting out of dreams”. Abnormal behaviors include sleep
talking, yelling, limb movement, and complex motor activities. Patients with REM sleep
behavior disorder arouse from sleep to full alertness often with complete recall of fearful
dream content, which may involve being chased or attacked. The motor behavior exhibited
tends to correlate with dream content. REM sleep periods typically occur in the latter half of
the night. The most common symptom at time of presentation is injury of the patient or bed
partner. As a result of the behaviors, bed partners often simply move to another bed or
room. Also, patients and families may have a sense of guilt or shame regarding the
behaviors, even though the behaviors may not be consistent with patients’ personalities.
This is particularly true when sexual behaviors are involved. Sleep disruption and daytime
sleepiness are often part of the history. REM sleep behavior disorder tends to be a disease
that occurs in older men, although women and people of all ages may be affected. The
reason for the strong predominance toward men, with an approximately nine-to-one mento-
women ratio, is not clearly known. The average age of onset is between 52.4 years to 60.9
years. Unlike those who experience sleep terrors, the victim will recall vivid dreams. The
frequency of these episodes varies from once every few weeks to several times a night.
Episodes tend to occur 90 min or more after sleep onset, when the first REM period typically
begins. (Mahowald et al., 2005).
REM sleep behavior disorder has been linked to a number of other neurological conditions;
thus, a careful review of systems and a physical examination are crucial. Polysomnographic
monitoring in patients with REM sleep behavior disorder reveals increased tonic and/or
phasic electromyographic activity, often accompanied by muscle twitching, extremity
flailing, or vocalization during REM sleep. REM sleep behavior disorder is often associated
with a growing number of underlying neurologic disorders, and may be induced by
numerous medications, particularly selective serotonin reuptake inhibitors (Boeve et al.,
REM sleep behavior disorder can be controlled with medication. Clonazepam is the
mainstay in the treatment of REM sleep behavior disorder and leads to either a complete or
partial response in approximately 90% of cases. Before it is prescribed, the potential benefits
of treatment should be weighed against the possible side effects. Other medications have
been tried when clonazepam is not effective or is poorly tolerated. Discussions related to
safety are very important, because precautionary measures may prevent serious injury to
the patient or family members (Schenck et al., 2002).
5.6 Other parasomnias
Ten disorders are classified under this category (Table 1). The most common are sleep
bruxism, sleep enuresis, and primary snoring.
Sleep bruxism is the third most common parasomnia and it can be bothersome to the bed
partner. Bruxism is not a dangerous disorder. However, it can cause permanent damage to
the teeth and uncomfortable jaw pain, headaches, or ear pain. Approximately 8.2% of
people experience it at least once a week. Sleep apnea and anxiety disorders are the most
prominent risk factors for bruxism. Bruxism could be a reflex to open the airway after an
apneic or hypopneic event. Bruxism may improve with treatment of sleep apnea with
continuous positive airway pressure. Sleep bruxism does not have a definite cure. The goals
of treatment are to reduce pain, prevent permanent damage to the teeth, and reduce
clenching as much as possible. Stress reduction, relaxation, biofeedback, hypnosis and
improvement of sleep hygiene have been tried with no persistent or significant
improvement. To prevent damage to the teeth, mouth guards or appliances (splints) have
been used since the 1930s to treat teeth grinding, clenching, and TMJ disorders. A splint may
help protect the teeth from the pressure of clenching. Pharmacologic interventions are
indicated for short-term management of patients who experience complications of sleep
bruxism, including pain in the temporomandibular joint. Benzodiazepines could be effective
because of their muscle-relaxing and anti-anxiety properties. Additionally, they increase the
arousal threshold that could precede teeth grinding. (Farid et al., 2004)
Sleep enuresis, more commonly known as bedwetting, refers to the lack of ability to
maintain urinary control during sleep. This recurrent involuntary urination is also called
nocturnal enuresis, which is characterized by at least two occurrences per month in 3 to 6
years old infants and at least one occurrence per month for older children. Sleep enuresis
is observed in 10% of children at the age of 6. The prevalence decreases with age.
Approximately 77% of children had enuresis when their parents were enuretic, whereas
44% of children with one parent who was enuretic developed enuresis. Simple behavior
modifications can be very effective treatments for children with enuretic episodes. For
example, intake of liquids and dietary bladder irritants such as citrus products should be
discouraged before bedtime. Taking note of when the enuresis actually occurs, and
waking and taking the child to toilet before that hour, can also be very helpful Matthias et
Psychological treatments such as encouragement of self-reliance, participation in
management, inculcation of self-respect and responsibility are also recommended by many
experts. Physical punishments and coercion, on the other hand, are considered to be the
most counterproductive measures and should be avoided at all costs.
Using devices such as bedwetting alarms and moisture alarms, combined with bladder
muscle exercises, dietary changes, retention control training etc can also be helpful remedies
in treating sleep enuresis. Education, encouragement, and patience are prudent approaches
for younger children. For older children who may be embarrassed by the occurrences, and
who may be affected by the emotional concerns, more aggressive treatment is
recommended. Biofeedback, including enuresis alarms, arousal training and desmopressin
have been tried with prominent success rates, although they are associated with high
relapse rates. Hypnotherapy and imipramine have been somewhat helpful in the
management Schenck et al., 1996).
Primary snoring is reported in 40% to 50% of people over the age of 65 and approximately
25% of the middle-age group. Snoring is usually a symptom of sleep disordered breathing.
Oral appliances and otolaryngologic procedures, including velopharyngeal surgery, can
effectively resolve snoring. Most of the studies on oral appliances are conducted for
treatment of obstructive sleep apnea syndrome, with no clear data on primary snoring. They
have decreased the frequency of snoring by 50%.
6. Treatment options
The primary therapy for disorders of arousal is reassurance and prevention. For most, the
disease course is usually benign and tends to resolve spontaneously with time. It is essential
that both the patient and bed partner be educated about safety precautions for the home and
bedroom environment, such as reducing or eliminating potential sources of injury (e.g.,
relocating the bedroom to a room on the ground floor, securing doors, using heavy
draperies over the windows, removing mirrors, and keeping the floor free of objects that the
sleepwalker might potentially trip over). Bed partners should be counseled not to attempt to
stimulate the patient during an episode as this may trigger violent behavior.
A trial of sleep extension or scheduled awakening may be considered. With scheduled
awakening, the patient is awakened just before the typical time of the parasomnia episode
and thereafter allowed to return to sleep.
Relaxation training and guided imagery may be helpful strategies for some patients,
especially those with disorders of arousal or rhythm movement disorders.
When the events are frequent or particularly dramatic, medication with a long- or mediumacting
benzodiazepine, such as clonazepam, at bedtime is effective therapy in most cases of
non-REM disorders of arousal and REM sleep behavior disorder. In non-REM disorders,
pharmacologic agents that have been used with some success include paroxetine and
trazodone and low-dose benzodiazepines. Typically, medication should be used in
combination with nonpharmacologic treatments after such techniques have been tried and
found to be ineffective and only when the sleep disorder is affecting daytime function.
Although parasomnias can be distressing and it is important to recognize that parasomnias
are diagnosable and treatable in the vast majority of patients. With recent understanding of
the sleep stages and transition of these stages, many of the parasomnias are readily
diagnosable and treatable.
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Edited by Dr. Chris Idzikowski
Hard cover, 190 pages
Published online 14, March, 2012
Published in print edition March, 2012
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concentrating on different focus groups, from adults to pregnant women, adolescents, children and
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