eMedicine Specialties > Psychiatry > Adult

Parasomnias

Author: Sat Sharma, MD, FRCPC, FACP, FCCP, DABSM, Program Director, Associate Professor, Department of Internal Medicine, Divisions of Pulmonary and Critical Care Medicine, University of Manitoba; Site Director of Respiratory Medicine, St Boniface General Hospital
Contributor Information and Disclosures

Updated: Apr 4, 2007

Introduction

Background

Parasomnias are disorders characterized by undesirable motor, verbal, or experiential phenomenon occurring in association with sleep, specific stages of sleep, or sleep-awake transition phases. Parasomnias may be categorized as (1) primary parasomnias, which are the disorders of sleep states and are further classified according to the sleep state of origin, rapid eye movement (REM), or non–rapid eye movement (NREM) or (2) secondary parasomnias, which are disorders of other organ systems that may manifest during sleep, eg, seizures, respiratory dyskinesias, arrhythmias, and gastroesophageal reflux.

Two major types of primary sleep disorders are described: dyssomnias and parasomnias. Primary sleep disorder is a malady of sleep that does not appear to be secondary to a physical or mental illness and is not substance-induced. Unlike dyssomnias, which are characterized by abnormal sleep quality, including initiation, maintenance, duration, timing, and amount of sleep, parasomnias are distinguished by deviant behavioral and/or physiologic events. These abnormalities/events are reliably associated with either the sleep/wake interface or certain sleep stages. Additionally, parasomnias manifest by activation of systems, such as the autonomic nervous system, or programs, such as cognitive, behavioral, or motor program stimulation.

The parasomnias have been subdivided according to 2 major classification schemes, the American Psychiatric Association's Diagnostic Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) and the American Sleep Disorders Association's International Classification of Sleep Disorders (ICSD). Four major types of parasomnias are included in the DSM-IV-TR. They include (1) nightmare disorder, (2) sleep terror disorder, (3) sleepwalking disorder, and (4) parasomnias not otherwise specified. However, the ICSD subdivides the parasomnias into 3 groups according to the sleep state of origin. They include (1) REM, (2) NREM, and (3) miscellaneous (ie, not respecting the sleep state).

The 5 disorders that are primarily discussed in this article are nightmare disorder, sleep terror disorder, sleepwalking disorder, REM sleep behavior disorder, restless legs syndrome (RLS), and periodic limb movement disorder (PLMD).

Nightmare disorder: Also called dream anxiety attacks, these are frightening dreams that occur during REM sleep and are associated with tachycardia, tachypnea, diaphoresis, and arousal. Complete alertness and subsequent recollection of the dreams differentiates nightmares from sleep terrors. Note that nightmares are another form of dreams except with documented emotional and physiological consequences.

Sleep terror disorder: Sleep terror is a disorder of arousal that primarily occurs during stages III and IV of NREM sleep. Sleep terror manifests as extreme panic and a loud scream during sleep, followed by motor activities such as hitting objects or moving in and out of the bedroom. Subsequent recollection of these episodes either does not occur or is partial.

Sleepwalking disorder: Again, this disorder arises from slow-wave stages of NREM sleep. The subject performs complex automatic behaviors, such as wandering aimlessly, carrying objects, going outdoors, and performing other activities of varying complexity and duration.

REM sleep behavior disorder: REM sleep behavior disorder is dream-enacting behavior that includes talking, yelling, punching, kicking, sitting, jumping out of bed, arm flailing, and grabbing. An acute form may occur during withdrawal from ethanol or sedative-hypnotic drugs. The chronic form presents for evaluation following observations of bed partners.

RLS and PLMD: These are common disorders that often may coexist. RLS primarily presents as insomnia, whereas PLMD is a well-recognized cause of excessive daytime somnolence. Nearly all patients with RLS have periodic limb movements, and only a minority of patients with PLMD also have RLS.

Two parasomnias recently validated and more extensively described in the literature are (1) somnambulistic sexual behavior, or sexsomnia, and (2) night eating disorder.

Sexual behaviors of all types may occur during sleepwalking. Somnambulistic sexual behavior (also called sexsomnia, sleep sex) is considered a variant of sleepwalking disorder. Sexual behavior during a sleep automatism can vary from explicit sexual vocalizations, to violent masturbation, to complex sexual acts including anal, oral, and vaginal penetration. A recent series described 11 patients with distinct behaviors of the sexual nature during sleep. The features are in common with other NREM arousal parasomnias. Medicolegal issues had occurred in a small number of cases. This behavior is more common than previously thought because a significant number of patients with this unusual parasomnia behavior were identified only after specific questions were asked.

The night eating syndrome (NES) was first described by Stunkard et al in 1955. No uniform definition of NES has yet been adopted. Evening hyperphagia originally is the main criterion, which implies that the amount of food consumed is excessive at this time of the day. However, definitions vary in terms of the amount of food consumed, the time frame involved, and whether the evening meal (dinner) is included or not.

The current definition focuses on NES to be present if patients report: (1) skipping breakfast >4 d/wk, interpreted as morning anorexia; (2) consuming more than 50% of total daily calories after 7 pm; and (3) difficulty falling asleep or staying asleep >4 d/wk. Whether NES should be differentiated from nocturnal eating syndrome is not clear in the literature. However, the terms may be defined distinctly as (1) night eating syndrome (defined as morning anorexia, evening hyperphagia, and insomnia) and (2) nocturnal eating syndrome (defined as eating at night after having gone to bed).

Pathophysiology

Human life encompasses 3 completely different states of existence: wakefulness, REM sleep, and NREM sleep. Sleep is not simply the passive absence of wakefulness; it is an extensive reorganization of CNS activities occurring during sleep. Each state of being is controlled by its unique neuroanatomic, neurophysiologic, and neurochemical association.

Wakefulness and REM and NREM sleep states overlap as transition occurs from one state to another. A large number of neural networks, neurotransmitters, and neurochemicals must be recruited concurrently to assert a given state of existence. Dissociation of these states and the admixture of state-determining variables are the mechanisms that set primary sleep parasomnias in motion. For example, intrusion of NREM sleep during wakefulness may produce sleep drunkenness or microsleeps; occurrence of REM sleep during wakefulness generates cataplexy or wakeful dreaming; loss of muscle atonia during REM sleep sets off acting out of dreams, termed REM behavior disorder.

The pathophysiology of parasomnias is unknown, although considerable speculation exists about the role of various functional systems in each disorder. Abnormalities in the normal regulation of different phases of sleep may be present. Some disorders, such as sleep terror and sleepwalking disorders, primarily are disturbances of slow-wave sleep, whereas sleep paralysis and REM behavior disorders are those of REM sleep. Others, such as rhythmic movement disorder (eg, head banging) are those of sleep-wake transition. Because the pattern of activation of parasomnias may resemble epilepsy (abrupt onset, confusion, disorientation, and amnesia for the event period), parasomnias originally were considered a form of epilepsy. Gastaut and Broughton's elegant work in 1965 and Broughton's work published in 1968 established the nonepileptic nature of parasomnias.

Rapid eye movement sleep behavior disorder

The physiologic phenomena that occur during REM sleep can be categorized as tonic and phasic. Tonic phenomena appear throughout an REM period. Examples include electromyographic (EMG) suppression and low-voltage electroencephalography (EEG). The phasic phenomena occur intermittently during an REM period. Examples include rapid eye movements and variability of cardiac cycle and respiratory function.

The tonic and phasic processes have been observed to be variously dissociated and recombined across different states. In contrast to wakefulness, which is characterized by consciousness and muscle tone, REM sleep is associated with dreaming and muscle atonia. Generalized atonia of REM sleep probably is caused by active inhibition of motor activity by centers identified to be present in the pons. REM sleep behavior can be experimentally produced in cats by bilateral pontine tegmental lesions, which are associated with the absence of REM atonia. However, in humans, a structural neuropathology is not necessary for REM behavior disorder because most patients do not have an identifiable neurological disorder. Therefore, functional dysregulation by depression of brainstem structures is responsible for atonia. The reduced activity of structures responsible for inhibiting phasic activity in the brain stem further contributes to the clinical manifestations of REM sleep behavior disorder.

Restless legs syndrome and periodic limb movement disorder

RLS and PLMD may be 2 clinical manifestations of the same CNS dysfunction. The neurophysiological mechanisms responsible for these disorders are not well described. PLMD occurs with a striking periodicity, suggesting that an underlying CNS pacemaker may be operative. Several observations have suggested that PLMD likely originates in the subcortical region and is regulated by rhythmic fluctuations at the brainstem level.

Both of these disorders may be the behavioral manifestation of CNS processes that become disinhibited. Patients with these disorders also may have a lower arousal threshold. Polysomnographic recordings exhibit periodic arousing stimuli leading to K complexes, followed by alpha activity, and then leg movements. The neuropharmacological hypothesis supports that an impaired CNS dopaminergic mechanism also may be involved. The deficiency of dopamine binding sites or low concentrations of dopamine and homovanillic acid have been found in several populations who have PLMD.

Single-photon emission computed tomography (SPECT) studies of the brain have identified defects in striatal dopamine D2 receptors. Other studies have pointed out an abnormality of the endogenous opioid system and abnormalities in iron metabolism with ferritin deficiency. Recent studies have reported low tissue iron content in substantia nigra and red nuclei on brain MRI scans of RLS patients. Consequently, interactions between the opioid and dopamine systems that occur in the basal ganglia, brainstem, and spinal cord contribute to the genesis of RLS and PLMD.

Frequency

United States

• Nightmare disorder: Of children aged 3-5 years, 10-50% may have this disorder. The prevalence in adults is unknown, although up to 50% of adults report occasional nightmares.
• Sleep terror disorder: Information regarding frequency is limited at best. The DSM-IV estimates the prevalence rate to be 1-6% in children and less than 1% in adults.
• Sleepwalking disorder: The criterion-based disorder is estimated to occur in 5% of children, but episodes of the disorder have been documented in as many as 30% of clinical samples of children and 7% of clinical samples of adults.
• REM sleep behavior disorder: The disorder may be rare; however, because many other sleep disorders, in particular the other parasomnias, may be misdiagnosed as REM sleep behavior disorder, the true prevalence is not known. It is diagnosed most often in the sixth or seventh decade of life. This disorder often is familial. As many as 60% of patients presenting to sleep clinics may have a positive family history. Men and women are affected equally. Although not proven, autosomal dominant transmission is expected. A telephone survey has shown an overall prevalence rate of violent behaviors during sleep of 2%, approximately one quarter of these likely were REM sleep behavior disorder, indicating REM sleep behavior disorder has an overall prevalence rate of 0.5%.
• RLS and PLMD: The prevalence rate of RLS is estimated to be as high as 10% in the general population and increases with age. The prevalence of PLMD also increases with age, 5% of the population aged 30-50 years has PLMD, compared to 30% of the population older than 50 years and 40% of the population older than 65 years. PLMD has been reported to be responsible for insomnia in 17% of patients and hypersomnia in 11% of patients evaluated at sleep disorder clinics.

International

The prevalence rates are not known to be any different from US rates.

Mortality/Morbidity

• The death rate of these 3 parasomnias is quite low; few, if any, reliable statistics exist regarding mortality. Similarly, the morbidity associated with the parasomnias mostly is secondary, such as the consequences of sleepwalking, assaulting others while asleep, and sleep deprivation in caretakers.
• One specific morbidity issue is eating behavior associated with sleepwalking. The associated morbidity primarily relates to excessive food intake.
• Of note is the inclusion of 2 parasomnias in the ICSD, the hallmark of which is death. The first is sudden unexplained nocturnal death syndrome, which is most common in otherwise healthy young adults of Southeast Asian descent, such as Laotian, Kampuchean, and Vietnamese people. The other is the better-known sudden infant death syndrome.

Race

• Information regarding the racial distribution of parasomnias is not available.

Sex

• Women report nightmares more frequently, in a ratio of 2-4:1.
• Among children, sleep terror disorder is more prevalent in males than in females, but in adults, the ratio is even.
• Sleepwalking disorder occurs with equal frequency in both sexes.
• REM sleep behavior disorder is more prevalent in males, but the exact ratio is not known.
• The prevalence of RLS and PLMD is similar between men and women.

Age

• See Frequency for the differences in age distributions of the parasomnias.

Clinical

History

The history associated with each subtype of the parasomnias follows:

• Nightmare disorder (dream anxiety disorder)
• • The history is that of a frightening dream.
  • Arousal during the dream is common.
  • The presence of a dream is the essential feature that differentiates nightmare disorder from sleep terror disorder.
  • History of traumatic experiences (This is a key symptom of PTSD.)
• Sleep terror disorder (pavor nocturnus)
• • A sleep terror is characterized by a sudden arousal from NREM sleep (usually from slow-wave sleep) and associated autonomic and behavioral manifestations of fear.
  • Commonly, patients cry out or scream as they are aroused.
  • Significant autonomic hyperactivity is present, with tachycardia, tachypnea, flushing, diaphoresis, and increased muscle tone.
  • The patient is routinely unresponsive to external stimuli and, when awakened, is confused, disoriented, and amnestic regarding the event.
  • Incoherent vocalizations or micturition have been reported to accompany the event.
• Sleepwalking (somnambulism)
• • Episodes of sleepwalking are associated with behaviors that range from simply sitting up in bed to walking, possibly with associated complex behaviors such as eating. Talking behavior also has been noted during these episodes.
  • Upon awakening, the patient most often is confused and amnestic regarding the event.
  • The event occurs during NREM sleep (usually slow-wave sleep) and may be more common after sleep deprivation.
  • The event may spontaneously terminate, or, the patient may return to bed or lie down somewhere else and return to sleep without ever awakening.
• Rapid eye movement sleep behavior disorder
• • The hallmark if this disorder is the acting out of dreams. The behavior can include punching, kicking, leaping, and running from the bed. The most common reason for medical consultation is injury to the bed partner, although the effects of sleep disruption also can precipitate such consultation. The event occurs during REM sleep (the dreams), hence the name.
  • In patients with REM sleep behavior disorder, arousals from sleep to alertness and orientation occur rapidly and patients usually have a vivid recall of their dreams.
  • Following awakening, the patient's behavior and interactions are normal.
  • Acute and chronic forms exist. The acute form can emerge during withdrawal from ethanol or sedative-hypnotic abuse and with anticholinergic and other drug intoxication states.
  • Despite nocturnal behavior, few patients develop excessive daytime sleepiness or fatigue.
• Restless legs syndrome and periodic limb movement disorder
• • Patients with RLS describe discomfort in lower extremities, using terms such as "pulling, searing, crawling, creeping, and boring" to describe sensations. The symptoms usually occur at bedtime or during other periods of inactivity. These distressing symptoms are relieved by moving the legs, walking about, rubbing the legs, squeezing or stroking the legs, and by taking hot showers or baths. The symptoms may wax or wane over the patients lifetime. Patients with RLS commonly present with complaints of insomnia (difficulty initiating sleep), and, in severe cases, the disorder may cause depression and suicidal thoughts.
  • PLMD primarily occurs during sleep. This disorder is described as rhythmic extension of the great toe, associated with dorsiflexion of the ankle and light flexion of the knee and hip. Because PLMD occurs during sleep, these symptoms often are not appreciated by the patient. Patients often present with symptoms of excessive daytime sleepiness, initially during passive activities such as watching TV, being a passenger in a car, or reading. In later stages, patients may have excessive daytime sleepiness during activities requiring alertness, such as driving, operating machinery, or talking with people.
  • RLS and PLMD may occur even during childhood and present as attention deficit disorder with hyperactivity or as growing pains.
  • RLS and PLMD are present in a significant proportion of pregnant woman, and exacerbations are observed during menstruation and menopause.
  • These disorders are associated with numerous neurological conditions such as peripheral neuropathy, postpolio syndrome, spinal cord pathology, and various causes of myelitis.
  • RLS and PLMD affect 20-40% of patients with chronic renal failure who are on dialysis.
  • A history of iron-deficiency anemia also is quite common in these patients.
  • RLS and PLMD should be considered if a patient complains of insomnia or excessive daytime sleepiness.

Physical

In patients with parasomnias that are not attributable to a general medical condition, physical findings are either absent or nonspecific. The only physical findings that can be specific to one of these parasomnias would be those findings associated with complications of the sleep disorder, such as falling for a sleepwalker.

• Patients with RLS and PLMD may have physical signs of peripheral neuropathies and other neurological disorders, such as radiculopathy and spinal cord pathology. Thus, a detailed neurological and musculoskeletal examination must be performed.
• For diagnosis of REM sleep behavior disorder following a complaint from the patient or bed partner, a complete neurological and psychiatric examination should be conducted.
• Diagnostic guidelines for primary restless legs syndrome
• • Discomfort is present in both legs (tingling, prickling, tension, aching), accompanied by irresistible movements of the limbs.
  • Symptoms appear at rest, show a circadian pattern by occurring mainly in the evening, and can interfere with sleep onset.
  • The severity may vary from week to week and may occur in upper limbs.
  • Partial or complete relief is obtained by physical maneuvers such as rubbing, shaking, stomping, or walking.
  • Neurological symptoms or neurological signs are absent.
• DSM-IV-TR diagnostic criteria for nightmare disorder
• • Repeated awakenings from the major sleep period or naps occur, with detailed recall of extended and extremely frightening dreams, usually involving threats to survival, security, or self-esteem. The awakenings generally occur during the second half of the sleep period.
  • Upon awakening from the frightening dreams, the person rapidly becomes oriented and alert (in contrast to the confusion and disorientation observed in patients with sleep terror disorder and some forms of epilepsy).
  • The dream experience, or the sleep disturbance resulting from the awakening, causes clinically significant distress or impairment in social, occupational, or other important areas of functioning.
  • The nightmares do not occur exclusively during the course of another mental disorder (eg, a delirium, posttraumatic stress disorder) and are not due to the direct physiological effects of a substance (eg, a drug of abuse, a medication) or a general medical condition.
• DSM-IV-TR diagnostic criteria for sleep terror disorder
• • Recurrent episodes of abrupt awakening from sleep occur, usually during the first third of the major sleep episode, and begin with a panicky scream.
  • Intense fear and signs of autonomic arousal, such as tachycardia, rapid breathing, and sweating, occur during each episode.
  • Patients demonstrate relative unresponsiveness to efforts by others to comfort the person during the episode.
  • No detailed dream is recalled, and amnesia develops regarding the episode.
  • The episodes cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.
  • The disturbance is not due to the direct physiological effects of a substance (eg, a drug of abuse, a medication) or a general medical condition.
• DSM-IV-TR diagnostic criteria for sleepwalking disorder
• • Repeated episodes of rising from bed during sleep and walking about occur, usually during the first third of the major sleep episode.
  • While sleepwalking, the person has a blank staring face, is relatively unresponsive to the efforts of others to communicate with him or her, and can be awakened only with great difficulty.
  • Upon awakening (either from the sleepwalking episode or the next morning), the person has amnesia regarding the episode.
  • Within several minutes after awakening from the sleepwalking episode, mental activity or behavior is not impaired, although a short period of confusion or disorientation may be present.
  • The sleepwalking causes clinically significant distress or impairment in social, occupational, or other important areas of functioning.
  • The disturbances are not due to the direct physiological effects of a substance (eg, a drug of abuse, a medication) or a general medical condition.

Causes

Few if any specific etiologies exist for these parasomnias, but each has a number of predisposing factors, described as follows:

• Nightmare disorder
• • Personality disorders (most frequently schizotypal)
  • Relationship difficulties
  • Other stressors
  • Levodopa, beta-adrenergic agents, and withdrawal of REM-suppressing medications
• Sleep terror disorder
• • Fever
  • Sleep deprivation
  • CNS depressant medications
• Sleepwalking disorder
• • Possible hereditary/familial trend
  • Thioridazine, fluphenazine, perphenazine, desipramine, chloral hydrate, and lithium
  • Fever
  • Sleep deprivation and obstructive sleep apnea
  • Other disorders that disrupt slow-wave sleep
  • Internal stimuli such as a distended bladder
  • External stimuli such as noises
• Rapid eye movement sleep behavior disorder
• • Mostly idiopathic
  • Has been associated with dementia, subarachnoid hemorrhage, ischemic cerebrovascular disease, olivopontocerebellar degeneration, multiple sclerosis, and brain stem neoplasms
• Restless legs syndrome and periodic limb movement disorders
• • Mostly idiopathic
  • Iron-deficiency anemia
  • Pregnancy, menstruation, and menopause
  • Chronic renal failure
  • Osteoarthritis of the hips and knees
  • Drugs
    • Caffeine
    • Tricyclic antidepressants
    • Selective serotonin reuptake inhibitors
    • Dopamine receptor-blocking drugs
  • Neurological disorders
  • Peripheral neuropathies (diabetes, idiopathic or toxic)
  • Various causes of myelitis
  • Postpolio syndrome
  • Spinal cord pathology (syringomyelia, radiation-induced myelopathy)
  • Lumbar/sacral radiculopathy

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