Disorders of Arousal (From Non-Rapid Eye Movement Sleep)

CONFUSIONAL AROUSALS

Confusional arousals consist of mental confusion or confusional behavior during or following arousals from sleep, typically from slow-wave sleep in the first part of the night, but also upon attempted awakening from sleep in the morning.

The individual is disoriented in time and space, with slow speech, diminished mentation, and blunted response to questions or requests. There is often prominent anterograde and retrograde memory impairment. During confusional arousals, especially during forced awakenings, behavior may be very inappropriate, vigorous, highly resistive, or even violent and murderous, and episodes can last minutes to several hours. The individual may appear to be awake during some or most of a confusional arousal, despite the diminished cerebral reactivity to external stimuli, with reduced vigilance and impaired cognitive response. Behaviors can be simple and non-goal-directed, or complex and protracted, and may involve aggressive or violent behavior or inappropriate sexual activity with oneself or the bed partner.

SLEEPWALKING

Sleepwalking consists of a series of complex behaviors that are usually initiated during arousals from slow-wave sleep and culminate in walking around with an altered state of consciousness and impaired judgment.

Episodes often begin with sitting up in bed and looking about in a confused manner before walking; episodes can also begin with immediately leaving the bed and walking or even “bolting” from the bed and running. Frantic attempts to escape an imminent perceived or dreamed threat can occur. Agitated, belligerent, or violent behavior can also occur. The person may be difficult to awaken but, when awakened, is often confused. There is usually amnesia for these episodes, although adults can remember fragments of episodes and sometimes will have considerable recall for the events. Dreaming during sleepwalking is sometimes reported in adults, which constitutes a form of dream-enacting behavior that may be indistinguishable from RBD. Sleepwalking with vivid hallucinations has been reported in adults.

Since sleepwalking usually originates from slow-wave sleep, it most often emerges in the first third or first half of the sleep period. It may occur during other times of increased slow-wave sleep, such as during recovery sleep after sleep deprivation. The ambulation may terminate spontaneously, at times in inappropriate places, or the sleepwalker may return to bed, lie down, and continue to sleep without reaching alertness at any point. Sleeptalking and shouting can accompany these events. The eyes are usually open during an episode and, not uncommonly, are wide open with a confused “glassy” stare, in contrast to RBD, when the eyes are usually closed during an episode. An episode of sleepwalking can occasionally occur during a daytime nap.

SLEEP TERRORS

Sleep terrors consist of arousals from slow-wave sleep accompanied by a cry or piercing scream and autonomic nervous system and behavioral manifestations of intense fear.

There is often intense autonomic discharge, with tachycardia, tachypnea, flushing of the skin, diaphoresis, mydriasis, and increased muscle tone. The person usually sits up in bed; is unresponsive to external stimuli; and, if awakened, is confused and disoriented. However, bolting out of bed and running is not uncommon in adults and can also be associated with violent behaviors. Amnesia for the episode subsequently occurs, although sometimes there are reports of dream fragments or brief vivid dream images or hallucinations. In some adults, more elaborate dream imagery can be reported, especially in regard to a frightening encounter. The sleep terror episode may be accompanied by incoherent vocalizations. Sometimes there is prolonged inconsolability with a sleep terror in children or adults.

Support for the diagnosis is also provided by a history of episodes emerging in the first third of the sleep period, particularly in children. However, episodes in adults can occur throughout most of the sleep period, and can also be associated with some degree of dream recall—either fragments of frightening dreams involving imminent danger or more elaborate dream imagery that could manifest clinically as dream-enacting behaviors that resemble RBD.

Parasomnias Usually Associated With Rapid Eye Movement Sleep

RAPID EYE MOVEMENT SLEEP BEHAVIOR DISORDER (Including Parasomnia Overlap Disorder and Status Dissociatus)

REM sleep behavior disorder (RBD) is characterized by abnormal behaviors emerging during REM sleep that cause injury or sleep disruption. RBD is also associated with electromyographic (EMG) abnormalities during REM sleep. The EMG demonstrates an excess of muscle tone or phasic EMG twitch activity during REM sleep.

A complaint of sleep related injury is common with RBD, which usually manifests as an attempted enactment of distinctly altered, unpleasant, action-filled, and violent dreams in which the individual is being confronted, attacked, or chased by unfamiliar people or animals. Typically, at the end of an episode, the individual awakens quickly; becomes rapidly alert; and reports a dream with a coherent story, with the dream action corresponding to the observed sleep behaviors. The latter phenomenon is called isomorphism.

Sleep and dream related behaviors reported by history and documented during polysomnography include talking, laughing, shouting, swearing, gesturing, reaching, grabbing, arm flailing, slapping, punching, kicking, sitting up, leaping from bed, crawling, and running. Walking, however, is quite uncommon with RBD, and leaving the room is especially rare and probably accidental. The eyes usually remain closed during an RBD episode, with the person attending to the dream action and not to the actual environment; this is a major reason for the high rate of injury in RBD. Also, chewing, feeding, drinking, sexual behaviors, urination, and defecation have not been documented to occur in REM sleep, which mirrors the findings from an animal model of RBD.

Medical attention is usually sought after sleep related injury has occurred to either the person or the bed partner and rarely because of sleep disruption. Because RBD occurs during REM sleep, it usually appears at least 90 minutes after sleep onset unless there is coexisting narcolepsy, in which case RBD can emerge shortly after sleep onset during a sleep-onset REM period. Vigorous or violent episodes typically occur about once weekly but may occur as often as four times nightly for several consecutive nights or considerably longer. RBD is usually a longstanding and progressive disorder. There is an acute form of RBD that emerges during intense REM sleep rebound states, such as during withdrawal from alcohol and sedative-hypnotic agents, with certain medication use, or with drug intoxication.

RECURRENT ISOLATED SLEEP PARALYSIS

Recurrent isolated sleep paralysis is characterized by an inability to perform voluntary movements at sleep onset (hypnagogic or predormital form) or on waking from sleep (hypnopompic or postdormital form) in the absence of a diagnosis of narcolepsy. The event is characterized by an inability to speak or to move the limbs, trunk, and head. Respiration is usually unaffected. Consciousness is preserved, and full recall is present. An episode of sleep paralysis lasts seconds to minutes. It usually resolves spontaneously but can be aborted by sensory stimulation, such as being touched or spoken to, or by the patient making intense efforts to move. The frequency of episodes varies from once in a lifetime to several times a year.

NIGHTMARE DISORDER

Nightmare disorder is characterized by recurrent nightmares, which are disturbing mental experiences that generally occur during REM sleep and that often result in awakening.

Nightmares are coherent dream sequences that seem real and become increasingly more disturbing as they unfold. Emotions usually involve anxiety, fear, or terror but frequently also anger, rage, embarrassment, disgust, and other negative feelings. Dream content most often focuses on imminent physical danger to the individual but may also involve other distressing themes. Ability to detail the nightmare’s contents upon awakening is common in nightmare disorder. Because nightmares typically arise during REM sleep, they may occur at any moment that REM propensity is high. Multiple nightmares within a single sleep episode may occur and may bear similar themes. Nightmares arising either immediately following a trauma (acute stress disorder [ASD]) or one month or more after a trauma (posttraumatic stress disorder [PTSD]) can occur during NREM sleep, especially stage 2, as well as during REM sleep and at sleep onset. Posttraumatic nightmares may take the form of a realistic reliving of a traumatic event or depict only some of its elements.

Other Parasomnias

SLEEP RELATED DISSOCIATIVE DISORDERS

Sleep related dissociative disorders are dissociative disorders that can emerge throughout the sleep period during well-established EEG wakefulness, either at the transition from wakefulness to sleep or within several minutes after an awakening from stages 1 or 2 NREM sleep or from REM sleep.

Sleep related dissociative disorders comprise a sleep-related variant of dissociative disorders, which are defined in the DSM-IV as “…a disruption in the usually integrated functions of consciousness, memory, identity, or perception of the environment.” Of the five listed diagnostic categories contained within the dissociative disorders section of the DSM-IV, three categories to date have been documented with nocturnal dissociative disorders: dissociative identity disorder (formerly called multiple personality disorder), dissociative fugue, and dissociative disorder not otherwise specified. The similarity of the behaviors found with nocturnal dissociative disorders to the behaviors found with various parasomnias justifies their inclusion within the parasomnias section of ICSD-2 and indicates how they comprise a distinct sleep related variant of dissociative disorders.

SLEEP ENURESIS

Sleep enuresis is characterized by recurrent involuntary voiding that occurs during sleep. In sleep enuresis, recurrent involuntary voiding occurs at least twice a week during sleep after five years of age. The condition is considered primary in a child who has never been consistently dry during sleep for six consecutive months. Sleep enuresis is considered secondary in a child or adult who had previously been dry for six consecutive months and then began wetting at least twice a week for a period of at least three months. Though primary and secondary enuresis share the common symptom of voiding during sleep, they are understood as distinct phenomena with different etiologies.

SLEEP RELATED GROANING (Catathrenia)

Sleep related groaning is a chronic, usually nightly, disorder characterized by expiratory groaning during sleep, particularly during the second half of the night. Polysomnography reveals recurrent bradypneic episodes that emerge mainly during REM sleep: a deep inspiration is followed by protracted expiration when a monotonous vocalization is produced that closely resembles groaning. The bradypneic episodes with groaning often recur in clusters and are most abundant during the later REM sleep cycles. A minority of episodes emerge during NREM sleep. The groaning is an exclusively expiratory event and is not associated with any observed respiratory distress or anguished or emotional facial expression even though moaning and “mournful sounds” can occur. The expiratory sounds occur with the person lying in any position. These recurrent bradypneic episodes may closely resemble central sleep apneas, although there are usually distinguishable differences between the two conditions.

EXPLODING HEAD SYNDROME

Exploding head syndrome is characterized by a sudden loud imagined noise or sense of a violent explosion in the head occurring as the patient is falling asleep or waking during the night.

The event is variously described as a painless loud bang, an explosion, a clash of cymbals, or a bomb exploding but occasionally may be a less alarming sound. It is usually associated with a sense of fright, and many patients believe they are having a stroke. The number of attacks varies—from many on a single night to infrequent—with some patients reporting clustering of attacks over several nights followed by a gap of weeks to months. A high level of clinical distress can be associated with recurrent attacks, with concern about their underlying cause.

SLEEP RELATED HALLUCINATIONS

Sleep related hallucinations are hallucinatory experiences, principally visual, that occur at sleep onset or on awakening from sleep. Sleep related hallucinations are predominantly visual but may include auditory, tactile, or kinetic phenomena. Hallucinations at sleep onset (hypnagogic hallucinations) may be difficult to differentiate from sleep-onset dreaming. Hallucinations on waking in the morning (hypnopompic hallucinations) may arise out of a period of REM sleep, and patients may also be uncertain whether they represent waking or dream-related experiences. Complex nocturnal visual hallucinations may represent a distinct form of sleep related hallucinations. They typically occur following a sudden awakening, without recall of a preceding dream. They usually take the form of complex, vivid, relatively immobile, images of people or animals, sometimes distorted in shape or size. These hallucinations may remain present for many minutes but usually disappear if ambient illumination is increased. Patients are clearly awake but often initially perceive the hallucinations as real and frightening.

SLEEP RELATED EATING DISORDER

Sleep related eating disorder (SRED) consists of recurrent episodes of involuntary eating and drinking during arousals from sleep with problematic consequences.

The episodes of eating always occur in an involuntary or “out of control” manner after an interval of sleep. They typically occur during partial arousals from sleep with subsequent partial recall. Some patients cannot be easily brought to full consciousness during an episode of eating, as in classic sleepwalking, and may have no recall of having eaten during the night. On the other hand, some patients seemingly have considerable alertness during an episode and have substantial recall in the morning. Problematic features of the recurrent sleep related eating also include one or more of the following: consumption of peculiar forms or combinations of food, or of inedible or toxic substances (e.g., frozen pizzas, raw bacon, buttered cigarettes, cat food and salt sandwiches, coffee grounds, ammonia cleaning solutions); insomnia from sleep disruption; sleep related injury; morning anorexia and abdominal distention; and adverse health consequences, such as weight gain and obesity.

PARASOMNIA, UNSPECIFIED

This diagnosis is intended for parasomnias that cannot be classified elsewhere or for cases in which the physician has a clinical suspicion that an underlying psychiatric condition may cause the parasomnia. Thus, in many cases, “parasomnia, unspecified” is a temporary diagnosis given when the patient needs a sleep diagnosis before the underlying psychiatric condition can be diagnosed. Once the psychiatric diagnosis is established, that will become the sole diagnosis (unless the sleep complaint is unusually severe, needs the skills of a sleep specialist, or the relationship between the parasomnia and the supposed underlying condition is questionable). However, in other patients, an underlying psychiatric condition, while suspected, may not ever be established, and in those patients, “parasomnia, unspecified” should remain a permanent diagnosis.

PARASOMNIA DUE TO DRUG OR SUBSTANCE

The essential feature of this diagnosis is the close temporal relationship between exposure to a drug, medication, or biological substance and the onset of parasomnia signs and symptoms. The emergent parasomnia can be a de novo parasomnia, the aggravation of a chronic intermittent parasomnia, or the reactivation of a previous parasomnia. The parasomnias most predictably associated with medications or biological substances are the disorders of arousal, SRED, RBD and parasomnia overlap disorder.

A variety of medications and biological substances have been reported to trigger acute or chronic RBD, such as selective serotonin reuptake inhibitors, venlafaxine, tricyclic antidepressants, monoamine oxidase inhibitors, mirtazapine, bisoprolol, selegiline, or cholinergic treatment for Alzheimer’s disease, Acute RBD can also be seen during states of withdrawal from cocaine, amphetamine, alcohol, barbiturate, and meprobamate abuse. Caffeine and chocolate abuse have been implicated in causing or unmasking RBD. Also, the use of medications such as â-adrenergic receptor-blocking agents can be associated with sleep related hallucinations.

PARASOMNIA DUE TO MEDICAL CONDITION

The essential feature of this diagnosis is that a parasomnia emerges as a manifestation of an underlying neurological or medical condition. RBD is the parasomnia most commonly associated with an underlying neurological condition (“symptomatic RBD”). The disorders of arousal, medical and neurological disorders and their treatment, or the premenstrual state, can precipitate their onset, or they can trigger their recurrence.

Dream enactment (“oneirism”) that is REM-sleep related or related to a dissociated REM sleep-wakefulness state can be a core feature of a pathologic condition called agrypnia excitata that is characterized by generalized motor overactivity, impaired ability to initiate and maintain sleep (with “wakeful dreaming”), loss of slow-wave sleep, and marked motor and autonomic sympathetic activation. Agrypnia excitata is found with such diverse conditions as delirium tremens, Morvan’s fibrillary chorea, and fata familial insomnia. Thus, agrypnia excitata manifests as both a severe parasomnia and a severe insomnia.

Complex nocturnal sleep-related (hypnagogic and hypnopompic) visual hallucinations can occur with neurological disorders such as narcolepsy, Parkinson’s disease, dementia with Lewy bodies, visual loss (Charles Bonnet hallucinations), and midbrain and diencephalic pathology (peduncular hallucinosis). Dreaming and sleep paralysis may or may not be associated with these hallucinations.

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Source: American Academy of Sleep Medicine, International Classification of Sleep Disorders, 2nd ed.: Diagnostic and Coding Manual, Westchester, Illinois: American Academy of Sleep Medicine, 2005.