Sleepwalking
Sleepwalking, also known as somnambulism or noctambulism, is a phenomenon of combined sleep and wakefulness. It is classified as a sleep disorder belonging to the parasomnia family. It occurs during the slow wave stage of sleep, in a state of low consciousness, with performance of activities that are usually performed during a state of full consciousness. These activities can be as benign as talking, sitting up in bed, walking to a bathroom, consuming food, and cleaning, or as hazardous as cooking, driving a motor vehicle, violent gestures and grabbing at hallucinated objects.
Although sleepwalking cases generally consist of simple, repeated behaviors, there are occasionally reports of people performing complex behaviors while asleep, although their legitimacy is often disputed. Sleepwalkers often have little or no memory of the incident, as their consciousness has altered into a state in which memories are difficult to recall. Although their eyes are open, their expression is dim and glazed over. This may last from 30 seconds to 30 minutes.
Sleepwalking occurs during slow-wave sleep of non-rapid eye movement sleep cycles. It typically occurs within the first third of the night when slow-wave sleep is most prominent. Usually, it will occur once in a night, if at all.
Signs and symptoms
Sleepwalking is characterized by:- partial arousal during non-rapid eye movement sleep, typically during the first third of the night
- dreamy content that may or may not be recalled when awake
- dream-congruent motor behavior that may be simple or complex
- impaired perception of the environment
- impaired judgement, planning and problem-solving.
Associated disorders
Most studies look at sleep disorders in adults, but children can also be affected. In the ten percent of the population that experience sleep-related disorders, children are most affected due to their developing brains. A study conducted in Australia, looked at sleepwalking and its association with sleep behaviors in children. It was found that sleepwalking could be associated with children's bedtime routines. Those who have behavioral problems are more likely to develop a sleep disorder and should be assessed. The relationship between sleepwalking and the behavioral and emotional problems are more associated than their bedtime routines. This may very well be because sleep related disorders and sleepwalking happen simultaneously; one cannot exist without the other.In the study "Sleepwalking and Sleep Terrors in Prepubertal Children" it was found that, if a child had another sleep disordersuch as restless leg syndrome or sleep-disorder breathing there was a greater chance of sleepwalking. The study found that children with chronic parasomnias may often also present SDB or, to a lesser extent, RLS. Furthermore, the disappearance of the parasomnias after the treatment of the SDB or RLS periodic limb movement syndrome suggests that the latter may trigger the former. The high frequency of SDB in family members of children with parasomnia provided additional evidence that SDB may manifest as parasomnias in children. Children with parasomnias are not systematically monitored during sleep, although past studies have suggested that patients with sleep terrors or sleepwalking have an elevated level of brief EEG arousals. When children receive polysomnographies, discrete patterns should be sought; apneas are rarely found in children. Children's respiration during sleep should be monitored with nasal cannula or pressure transducer system or esophageal manometry, which are more sensitive than the thermistors or thermocouples currently used in many laboratories. The clear, prompt improvement of severe parasomnia in children who are treated for SDB, as defined here, provides important evidence that subtle SDB can have substantial health-related significance. Also noteworthy is the report of familial presence of parasomnia. Studies of twin cohorts and families with sleep terror and sleepwalking suggest genetic involvement of parasomnias. RLS and SDB have been shown to have familial recurrence. RLS has been shown to have genetic involvement.
Sleepwalking may also accompany the related phenomenon of night terrors, especially in children. In the midst of a night terror, the affected person may wander in a distressed state while still asleep, and examples of sufferers attempting to run or aggressively defend themselves during these incidents have been reported in medical literature.
In some cases, sleepwalking in adults may be a symptom of a psychological disorder. One study suggests higher levels of dissociation in adult sleepwalkers, since test subjects scored unusually high on the hysteria portion of the "Crown-Crisp Experiential Index". Another suggested that "A higher incidence has been reported in patients with schizophrenia, hysteria and anxiety neuroses". Also, patients with migraine headaches or Tourette syndrome are 4–6 times more likely to sleepwalk.
Consequences
During the amnesic state sleepwalkers are in, many things can happen without their recollection. One thing that can happen is a sleep disorder called sexsomnia, where an individual can engage in sexual behaviors with oneself or others. Its occurrence is rare, but can happen during sleepwalking. Sleep-related eating disorder, in which sleepwalkers eat involuntarily, can also happen. The events can include eating/drinking regular foods or odd combinations of food. Insomnia and daytime sleepiness can also occur. Most sleepwalkers get injuries at some point during sleepwalking, often minor injuries such as cuts or bruises. In rare occasions, however, sleepwalkers have fractured bones and died as the result of a fall. Sleepwalkers may also face embarrassment of being found naked in public.Causes
The cause of sleepwalking is unknown. A number of, as yet unproven, hypotheses are suggested for why it might occur, including: delay in the maturity of the central nervous system, increased slow wave sleep, sleep deprivation, fever, and excessive tiredness. There may be a genetic component to sleepwalking. One study found that sleepwalking occurred in 45% of children who have one parent who sleepwalked, and in 60% of children if both parents sleepwalked. Thus, heritable factors may predispose an individual to sleepwalking, but expression of the behavior may also be influenced by environmental factors. Genetic studies using common fruit flies as experimental models reveal a link between night sleep and brain development mediated by evolutionary conserved transcription factors such as AP-2. Sleepwalking may be inherited as an autosomal dominant disorder with reduced penetrance. Genome-wide multipoint parametric linkage analysis for sleepwalking revealed a maximum logarithm of the odds score of 3.14 at chromosome 20q12-q13.12 between 55.6 and 61.4 cM.Sleepwalking has been hypothesized to be linked to the neurotransmitter serotonin, which also appears to be metabolized differently in migraine patients and people with Tourette syndrome, both populations being four to nine times more likely to experience an episode of sleepwalking. Hormonal fluctuations have been found to contribute to sleepwalking episodes in women, with the likeliness to sleepwalk being higher before the onset of menstruation. It also appears that hormonal changes during pregnancy decrease the likelihood of engaging in sleepwalking.
Medications, primarily in four classes—benzodiazepine receptor agonists and other GABA modulators, antidepressants and other serotonergic agents, antipsychotics, and β-blockers—have been associated with sleepwalking. The best evidence of medications causing sleepwalking is for zolpidem and sodium oxybate; all other reports are based on associations noted in case reports.
A number of conditions, such as Parkinson's disease, are thought to trigger sleepwalking in people without a previous history of sleepwalking.
Diagnosis
is the only accurate assessment of a sleepwalking episode. Because this is costly and sleepwalking episodes are usually infrequent, other measures commonly used include self-, parent-, or partner-report. Three common diagnostic systems that are generally used for sleepwalking disorders are International Classification of Diseases, the International Classification of Sleep Disorders, and the Diagnostic and Statistical Manual.The Diagnostic and Statistical Manual defines two subcategories of sleepwalking, although sleepwalking does not need to involve either behaviours:
- sleepwalking with sleep-related eating.
- sleepwalking with sleep-related sexual behavior.