Somnambulism is the medical term used for sleepwalking that includes undesirable actions such as walking, that occur during abrupt but limited arousals from deep non-rapid eye movement (NREM) slow-wave sleep.
Somnambulism is characterized by:
Somnambulism has been associated with various other sleep disorders such as confusional arousals, rhythmic movement disorders, night terrors in children, somniloquy (sleep talking) and bruxism (teeth grinding), as well as daytime fatigue, and emotional and behavioral issues in children.
Evidence for a genetic predisposition for sleepwalking has been observed in some patients. Monozygotic twins have a higher chance of somnambulism than dizygotic twins. More Whites with somnambulism are found to be positive for the DQB1*0501 gene as compared to Whites without somnambulism, which suggests that DQB1 genes are involved in motor disorders in sleep. Some studies have also indicated that sleepwalking may have an autosomal dominant mode of inheritance, exhibiting reduced penetrance. Some classes of medications such as antibiotics, anticonvulsants, antidepressants, benzodiazepines, lithium, antipsychotics, selective serotonin reuptake inhibitors (SSRIs), quinine, beta-blockers, and tricyclic antidepressants (TCAs) have been shown to trigger episodes of sleepwalking in patients with no previous history of somnambulism. Specifically, the benzodiazepine receptor agonist zolpidem has been strongly associated with sleepwalking even without a prior history. Prolonged sleep deprivation, specifically more than 24hrs, promotes sleepwalking in predisposed individuals. Sleepwalking events are more explicit and complex behaviors when they follow sleep deprivation. Hyperthyroidism has also been shown to cause sleepwalking in a few cases.
Somnambulism is a common arousal disorder. However, the epidemiology of this disorder is still ambiguous. The prevalence rate of sleepwalking is significantly higher in children than in adults. A systematic review and meta-analysis by Stallman and colleagues showed the estimated lifetime prevalence of sleepwalking is 6.9% without significant difference in lifetime reports of sleepwalking between children and adults. The prevalence of sleepwalking, within the past 12 months, was reported significantly higher in children 5.0% compared to 1.5% in adults. This is likely related to less slow-wave sleep during adulthood, leading to fewer prospects for sleepwalking. Sleepwalking usually occurs in children, but it can continue into adulthood or appear de novo among the adult population. Studies suggest that relatively few people start sleepwalking as adults, and adult-onset somnambulism is usually associated with medications and neurodegenerative diseases.
Studies indicate decreased localized cerebral blood flow in the frontal and parietal areas of patients that sleepwalk as compared to controls. Moreover, restricted perfusion in the dorsolateral prefrontal cortex and insula is found to be congruous with the clinical signs of somnambulistic episodes. Changes in regional cerebral blood flow patterns occurring during the resting-state wakefulness of patients that sleepwalk may be related to functional problems observed in these patients, during the day time.
The majority of patients have a history of witnessed episodes of sleepwalking with no memory of the event. Sometimes, the spouse reports episodes of sleepwalking and performing actions such as relocating belongings in the room. There have also been reports of concomitant sleep talking and inappropriate sexual behavior during sleep. Other patients have presented with "abnormal activity at night," for example, waking up to find uneaten food left out in the kitchen in the morning. These behaviors are usually intermittent, and patients do not promptly seek medical attention. Physical examination fails to reveal any specific findings in the case of most patients.
Our knowledge of somnambulism is still in its early stages. Polysomnography is the most reliable method to diagnose somnambulism. However, it is not recommended for an initial assessment of the condition because of its high cost and inconvenience. There are difficulties in capturing infrequent and irregular behavior, such as sleepwalking. In most cases, a detailed history and reports from close contacts are enough to make a diagnosis of somnambulism. Polysomnography can be applied in forensic cases or when the differential diagnosis is uncertain. Moreover, a complete review of the patient's medications, thyroid function tests, and screening for neurodegenerative diseases such as Parkinsonism should be performed.
Somnambulism is a common arousal disorder that is mostly benign and does not require treatment. No clinical studies have been carried out to assess the efficacy of somnambulism treatments to date. However, it has been observed that scheduled waking or hypnosis exhibit the greatest benefit with the least adverse effects in cases where sleepwalking is causing distress to the patient or family.
Scheduled waking refers to waking the patient 15-30 minutes before their usual sleepwalking time. Hypnosis providing the hypnotic suggestion that the patient will wake up if they touch the ground with their feet, is based on a similar concept of interrupting the sleepwalking phenomenon. Both interventions have to be practiced every day for the duration of two to three weeks.
Safety precautions like locking windows and external doors and removing breakable objects are recommended to decrease the risk of injuries.
No medication has been approved for the treatment for sleepwalking, but clinical experience indicates some benefit of gamma-aminobutyric acid (GABA) enhancing agents like clonazepam or gabapentin if taken one hour before sleep.
The following conditions should be ruled out while making a diagnosis of somnambulism.
Somnambulism usually has a good prognosis for most of the patients. However, sometimes it can lead to bodily harm (e.g., falling from a height or walking through a glass window) and embarrassing situations (e.g., to be found naked wandering around in public). Children generally improve sleepwalking behavior by adolescence and usually do not require any interventions or medications.
Somnambulism is usually a benign condition in most of the cases. However, there have been some reports of injuries associated with sleepwalking. The majority of these patients did not need hospitalization, but major trauma is possible.
Patients presenting with somnambulism have the potential to harm themselves physically. Parents of children who sleepwalk must take steps to ensure the avoidance of unsafe situations, such as falling down the stairs or off balconies. Patients that sleepwalk should always have their bedrooms on the first floor of the house, and windows and doors must be firmly locked. When dealing with a child that sleepwalks, parents should not try any interventions and avoid slapping, shaking, or shouting at the child. Childhood sleepwalking behavior generally improves by adolescence without any interventions or medication.
Caregivers or spouses of patients that sleepwalk should be educated about scheduled awakenings. Parents of a child that sleepwalks can be instructed to keep a diary of the time of sleepwalking for several nights. Then they should start waking the patient 15 minutes prior to which the sleepwalking has been occurring and make sure the patient is fully awake for a few minutes. Similar patient education has been found to be effective in adult-onset sleepwalking and scheduled waking, which refers to waking the patient 15–30 minutes before their usual sleepwalking time has been reported to be helpful.
The patients with somnambulism may exhibit other signs and symptoms such as sleep talking and inappropriate sexual behavior during sleep. The underlying cause of somnambulism may be due to a wide variety of reasons including certain medications, neurodegenerative diseases, REM sleep behavior disorder, rare conditions such as Smith-Magenis syndrome, and even hyperthyroidism. While the physical exam in a sleepwalker may not reveal any significant findings, the potential cause is difficult to determine without proper investigations.
Primary care clinicians are frequently involved in the care of patients with somnambulism. Sometimes it is important to seek consultation from an interprofessional group of specialists that may include a pediatrician and a neurologist. The nurses and laboratory staff are also important members of the interprofessional team as they help with lab tests such as imaging and blood tests and help with the education of the patients and families. In cases where the evidence is not definitive or minimal, expert opinion from the specialist may be utilized to recommend the type of imaging or treatment. An interprofessional team approach will improve patient outcomes.
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