**4. Epidemiology**

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 behaviours 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., 1980).

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 week.

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.

Parasomnias 153

feeling complete isolation and fear. Parents often describe terrified facial expressions,

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 behaviour may range from simple ambulation with a "glassy stare" to more complex activities such as driving. Sleepwalking may be preceded by confusional

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

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

mumbling, shouting, and inability to be consoled.

**5.3 Sleepwalking** 

arousals or sleep terrors.

hypnosis (Farid et al, 2004).

**5.4 Nightmares** 

1971).

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 behaviour disorder tends to affect older adults, with a mean age of onset of 50 to 60 years, predominantly affecting males.

#### **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 disorder.

#### **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 behaviour (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 arousals.

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

Sleepwalking occurs more frequently in children with an estimated prevalence of up to 40

Prevalence of RBD is estimated to be about 0.5 per cent13. REM sleep behaviour disorder tends to affect older adults, with a mean age of onset of 50 to 60 years, predominantly

The disorders that are primarily discussed in this chapter are confusional arousals, sleep terror disorder, sleepwalking disorder, nightmare disorder and REM sleep behavior

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,

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

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

disorientation and occasional violent or inappropriate behaviour (Farid et al, 2004).

no indication to intervene during the episodes of confusional arousal (Young, 2008).

per cent in this age group. Prevalence among adults is about 4 per cent.

affecting males.

disorder.

**5.2 Sleep terror** 

arousals.

**5.1 Confusional arousals** 

**5. Clinical features and symptoms** 

feeling complete isolation and fear. Parents often describe terrified facial expressions, mumbling, shouting, and inability to be consoled.
