Introduction

Somnambulism is the medical term for sleepwalking, which includes undesirable actions such as walking, occurring during abrupt but limited arousals from deep non-rapid eye movement (NREM) and slow-wave sleep.[1] Somnambulism is characterized by:

• Incomplete arousal occurs during NREM sleep, usually during the earlier third of the night
• The ability or inability to recall dream content
• Simple or complex movements that are in congruence with a dream
• Diminished awareness of the environment
• Impaired decision-making ability, planning, and problem-solving skills[2]

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.[3][4]

Etiology

Evidence for a genetic predisposition for sleepwalking has been observed in some patients. Monozygotic twins have a higher chance of somnambulism than dizygotic twins.[5][6] A higher proportion of Whites with somnambulism are found to be positive for the DQB1*0501 gene compared to Whites without somnambulism, suggesting that DQB1 genes are involved in motor disorders during sleep.[7] Some studies have also suggested that sleepwalking may have an autosomal dominant mode of inheritance, characterized by reduced penetrance.[8] 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.[9] Specifically, the benzodiazepine receptor agonist zolpidem has been strongly associated with sleepwalking even without a prior history. Prolonged sleep deprivation, specifically more than 24 hours, promotes sleepwalking in predisposed individuals. Sleepwalking events are more explicit and complex behaviors that occur after sleep deprivation.[9] Hyperthyroidism has also been shown to cause sleepwalking in a few cases.[9][10]

Epidemiology

Somnambulism is a common arousal disorder. However, the epidemiology of this disorder remains unclear. The prevalence rate of sleepwalking is significantly higher in children than in adults. A systematic review and meta-analysis by Stallman and colleagues found an estimated lifetime prevalence of sleepwalking of 6.9%, with no significant difference in lifetime reports of sleepwalking between children and adults. The prevalence of sleepwalking within the past 12 months was reported to be significantly higher in children, 5.0% compared to 1.5% in adults. This is likely related to the reduced amount of slow-wave sleep during adulthood, which in turn leads to fewer opportunities for sleepwalking.[11] Sleepwalking usually occurs in children but can continue into adulthood or appear de novo among the adult population.[11][12] Studies suggest that relatively few people start sleepwalking as adults, and adult-onset somnambulism is usually associated with medications and neurodegenerative diseases.[13][14]

Pathophysiology

Studies indicate decreased localized cerebral blood flow in the frontal and parietal areas of patients who sleepwalk compared to those in the control group. Moreover, restricted perfusion in the dorsolateral prefrontal cortex and insula is congruous with the clinical signs of somnambulistic episodes. Changes in regional cerebral blood flow patterns occurring during the resting-state wakefulness of patients who sleepwalk may be related to functional problems observed in these patients during the daytime.[14]

History and Physical

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 often do not seek medical attention promptly. Physical examination fails to reveal any specific findings in most patients.[15][16]

Evaluation

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. A detailed history and reports from close contacts are usually enough to diagnose somnambulism. Polysomnography can be applied in forensic cases or when the differential diagnosis is uncertain.[2] Moreover, a complete review of the patient's medications, thyroid function tests, and screening for neurodegenerative diseases such as Parkinsonism should be performed.[9][10][13]

Treatment / Management

Somnambulism is a common arousal disorder that is primarily benign and does not require treatment. No clinical studies have been conducted to assess the efficacy of somnambulism treatments. However, scheduled waking or hypnosis exhibits the most significant benefit with the least adverse effects in cases where sleepwalking causes distress to the patient or their family. Scheduled waking refers to waking the patient 15-30 minutes before their usual time for sleepwalking. Hypnosis suggests that patients wake up if they touch the ground with their feet based on a similar concept of interrupting the sleepwalking phenomenon. Both interventions must be practiced daily for 2 to 3 weeks.[2] Safety precautions, such as locking windows and external doors, and removing breakable objects, are recommended to decrease the risk of injuries. No medication has been approved to treat sleepwalking. Still, clinical experience suggests some benefit from gamma-aminobutyric acid (GABA)- enhancing agents like clonazepam or gabapentin when taken 1 hour before sleep.

Differential Diagnosis

The following conditions should be ruled out while making a diagnosis of somnambulism.

• Neurodegenerative changes seen in Parkinson's disease at the brainstem level can cause arousal from NREM/REM sleep and affect locomotion and muscle tone, leading to several sleep-associated behavioral disorders, including somnambulism.[13]
• Somnambulism due to medications such as antibiotics, anticonvulsants, antidepressants, benzodiazepines, lithium, antipsychotics, SSRIs, quinine, beta-blockers, and TCAs has been observed.[9]
• REM sleep behavior disorder[17]
• Smith-Magenis syndrome: In addition to other findings, this syndrome presents with sleep disturbances characterized by changes in circadian rhythm, including frequent nighttime awakenings and daytime sleepiness, which cause significant distress to patients and their families.[18]

Prognosis

Somnambulism usually has a good prognosis for most patients. However, sometimes it can lead to bodily harm (eg, falling from a height or walking through a glass window) and embarrassing situations (eg, to be found naked wandering around in public).[2] Children generally improve sleepwalking behavior by adolescence and usually do not require any interventions or medications.

Complications

Somnambulism is usually a benign condition in most cases. However, there have been some reports of injuries associated with sleepwalking (eg, falling from a height or walking through a glass window). The majority of these patients did not need hospitalization, but major trauma is possible.[19]

Deterrence and Patient Education

Patients presenting with somnambulism have the potential to harm themselves physically. Parents of children who sleepwalk must take steps to prevent them from encountering unsafe situations, such as falling down the stairs or off balconies. Patients who 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 who sleepwalks, parents should not try any interventions and avoid slapping, shaking, or shouting at the child. Childhood sleepwalking behavior typically improves by adolescence without the need for interventions or medication. Caregivers or spouses of patients who sleepwalk should be educated about the importance of scheduled awakenings. Parents of a child who 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 before the sleepwalking and ensure the patient is fully awake for a few minutes.[20] Similar patient education is 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.[2]

Enhancing Healthcare Team Outcomes

Patients with somnambulism may exhibit other signs and symptoms, such as sleep talking and inappropriate sexual behavior during sleep.[15] 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.[9][10][13][18] While the physical examination of a sleepwalker may not reveal any significant findings, determining the potential cause can be challenging without proper investigation. Primary care providers are frequently involved in the care of patients with somnambulism.[21] Sometimes, it is essential to seek consultation from an interprofessional group of specialists, which may include a pediatrician and a neurologist. The nurses and laboratory staff are also important members of the interprofessional team, as they assist with laboratory tests, such as imaging and blood tests, and help educate patients and their 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.[13] An interprofessional team approach improves patient outcomes.

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Disclosure: Azka Zergham declares no relevant financial relationships with ineligible companies.

Disclosure: Zeeshan Chauhan declares no relevant financial relationships with ineligible companies.