Somnambulism (ie, sleepwalking) is a disorder of arousal that falls under the parasomnia group. Parasomnias are undesirable motor, verbal, or experiential events that occur during sleep. These phenomena occur as primary sleep events or secondary to systemic disease. They are categorized as those occurring in rapid eye movement (REM) sleep; those occurring during non–rapid eye movement (NREM) sleep; and miscellaneous types that do not relate to any specific sleep state.
Sleepwalkers often have little or no memory of the incident, as they are not truly conscious. Although their eyes are open, their expression is dim and glazed over. Sleepwalking may last as little as 30 seconds or as long as 30 minutes.
Pathophysiology
The parasomnias have been thought to represent not pathologic cerebral functioning but rather a response to CNS activation that results in sleep-wake or REM-NREM state confusion, instability, or overlap. Recent studies, however, demonstrate differences between sleep patterns and neuronal sleep control mechanisms in individuals with parasomnias compared with those without. Normal sleep involves cyclic hypnic patterns throughout the night between wakefulness, NREM, and REM states. The CNS remains active during all sleep-wake states, although rapid changes are required in neural networks, rhythms, and neurotransmitters with state changes. The length of each cycle averages 50 minutes for a full-term newborn, increasing to approximately 90 minutes by adolescence.
Slow wave sleep (SWS) normally occurs in the first 2 hypnic cycles; younger children have an additional SWS period toward the end of the sleep period. Children typically enter their deepest sleep within 15 minutes of sleep onset, and this first SWS period lasts from 45-75 minutes. This explains why it is easy to move children without rousing them soon after sleep onset. Parasomnias occur as children are caught in a mixed state of transition from one sleep cycle to the next (eg, NREM-wakefulness). This transition state is characterized by a high arousal threshold, mental confusion, and unclear perception.
Sleepwalkers appear to have an abnormality in slow wave sleep regulation. The dissociation that occurs between body and mind sleep appears to arise from activation of thalamocingulate pathways with persisting deactivation of other thalamocortical arousal systems. The first slow wave sleep period of the night is considered to be more disturbed in somnambulistic individuals, and the entire NREM-REM sleep cycle is more fragmented. Because these disorders occur more frequently in children, these differences have been suggested as signs of CNS immaturity.
Clinical Presentation
Episodes range from quiet walking about the room to agitated running or attempts to "escape." Subjects may later report attempting to escape dangerous situations or terrifying threats. Typically, the eyes are open with a glassy, staring appearance as the child quietly roams the house.
On questioning, responses are slow or absent. If returned to bed without awakening, the child usually does not remember the event. Older children, who may awaken more easily at the end of an episode, often are embarrassed by the behavior (especially if it was inappropriate).
Sleepwalking has no association with previous sleep problems, sleeping alone in a room or with others, achluophobia (fear of the dark), or anger outbursts.
Causes
Genetic
Sleepwalking occurs more frequently in monozygotic twins and is 10 times more likely if a first-degree relative has a history of sleepwalking.
An increased frequency of DQB1*04 and *05 alleles is reported. DQB1 genes have also been implicated in narcolepsy and other disorders of motor control during sleep such as REM behavior disorder.
Environmental: Sleep deprivation, chaotic sleep schedules, fever, stress, magnesium deficiency, and chemical or drug intoxication (eg, alcohol), sedative/hypnotics (eg, Zolpidem ), combination of valproic acid and zolpidem , antidepressants (eg, bupropion , paroxetine, amitriptyline), neuroleptics (eg, lithium, reboxetine), minor tranquilizers, stimulants, antibiotics (eg, fluoroquinolone), anti-Parkinson medications (eg, levodopa), anticonvulsants (eg, topiramate), and antihistamines can trigger parasomnias.
Physiologic
The length and depth of SWS, which is greater in young children, may be a factor in the increased frequency of parasomnias in children.
Conditions such as pregnancy and menstruation are known to increase frequency in patients with parasomnias.
Associated medical conditions
Arrhythmias
Chronic paroxysmal hemicrania
Migraine
Fever
Gastroesophageal reflux
Nocturnal asthma
Nocturnal seizures
Obstructive sleep apnea: Children with obstructive sleep apnea or Tourette syndrome are at greater risk of having parasomnias along with their underlying disorder.
Chronic sleepwalking, especially in adults, is frequently associated with sleep-disordered breathing. Treatment of the sleep-disordered breathing with continuous positive airway pressure (CPAP) or surgery typically improves or resolves the sleepwalking. Noncompliance with CPAP is associated with persistence or recurrence of sleepwalking. Serotonin has been postulated as the physiologic link between these two disorders.
Psychiatric disorders
Posttraumatic stress disorder
Panic attack
Dissociative states
Major depressive disorder
Obsessive-compulsive disorder
Hyperthyroidism : Thyrotoxicosis has been associated with an increased incidence of sleepwalking, and achievement of euthyroidism is associated with improvement or resolution of the symptoms. Sleepwalking may occur as an early symptom, and the onset of sleepwalking in a patient out of the normal expected age range should be evaluated for hyperthyroidism. The mechanism for the sleepwalking is considered to be increased fatigue in combination with longer periods of non-REM sleep.
Treatment
General guidelines
Reassurance is the mainstay of treatment. The benign nature of the events and subsequent disappearance in most cases should be emphasized.
If environmental or predisposing factors are discovered, an attempt should be made to eliminate them. Assure adequate sleep, regulation of sleep cycle, and treatment of underlying medical conditions (eg, gastroesophageal reflux, obstructive sleep apnea, periodic leg movements, seizures).
Avoid auditory, tactile, or visual stimuli early in the sleep cycle. These have been shown to induce events in some patients with parasomnias.
Instruct parents to lock windows and doors, remove obstacles and sharp objects from the room, and add alarms (if necessary) to decrease the likelihood of injury during an episode.
Depending on the situation, comforting the child and gently redirecting him or her to bed may be appropriate. Attempts to confront or wake up patients during the events frequently lengthens the parasomnia episode and may induce resistance or violence from the patient.
Pharmacological measures may be necessary in the following situations:
The possibility of injury is real.
-Continued behaviors are causing significant family disruption or excessive daytime sleepiness.
-Unusual symptoms are present.
-Nonpharmacological interventions have proven to be inadequate.
-Benzodiazepines, tricyclic antidepressants, and serotonin reuptake inhibitors have been shown to be useful. Clonazepam in low doses before bedtime and continued for 3-6 weeks is usually effective.
-Medication often can be discontinued after 3-5 weeks without recurrence of symptoms. Occasionally, frequency of episodes increases briefly after discontinuing the medication because of rebound sleep.
Nonpharmacological measures
-Relaxation techniques, mental imagery, and anticipatory awakenings are preferred for long-term management. The first 2 techniques should be undertaken only with the help of an experienced behavioral therapist or hypnotist.
-Anticipatory awakenings consist of waking the child approximately 15-20 minutes before the usual time of an event and then keeping him awake through the time during which the episodes usually occur.
Some studies suggest that children who sleepwalk may have been more restless sleepers when aged 4-5 years and more restless with more frequent awakenings during the first year of life.
