Clinical neurophysiology of NREM parasomnias

A population-based study exploring association of parasomnia symptoms with sleep onset delay among school-aged children

OBJECTIVE

Parasomnia is potentially implicated in sleep pattern and sleep architecture, however, evidence is quite limited. This study aimed to investigate the association between parasomnia symptoms and sleep onset delay among children through a large epidemiological study.

METHODS

Two rounds of cross-sectional studies were conducted among 21,704 children aged 3-11; one taking place in Shanghai and the other in Sanya, Hainan province. Children's sleep characteristics were evaluated using the Children's Sleep Habits Questionnaire (CSHQ). Propensity score matching was adopted to balance the difference of covariates, and the logistic regression models were implemented to examine the associations between parasomnia symptoms and sleep onset delay.

RESULTS

A total of 38.2 % of children had sleep onset delay. Parasomnias, especially non rapid eye movement (NREM) and rapid eye movement (REM) parasomnia symptoms, were associated with an increased risk of sleep onset delay (Sleep Walking: OR = 1.55; Sleep Terror: OR = 1.34; Nightmare: OR = 1.37, all p˂0.001). The similar findings were observed in stratified analyses according to sleep duration, and the association was pronounced in sleep sufficiency group (Sleep Walking: OR = 1.62; Sleep Terror: OR = 1.35; Nightmare: OR = 1.35, all p˂0.001). Moreover, a dose-dependent pattern was observed, in which cumulative parasomnia symptoms were associated with increasing risk of sleep onset delay (2 symptoms: OR = 1.19; ≥3 symptoms: OR = 1.40; by comparison with ≤1 symptom). All these findings were also similarly observed in the propensity score matching sample. Moreover, the associations were generally established in both Shanghai and Sanya children.

CONCLUSIONS

Parasomnia symptoms were associated with a higher risk of sleep onset delay independently of sleep duration among children. More studies are needed to enrich the current evidence, thus further clarifying the association and interaction among different sleep parameters.

From physiological awakening to pathological sleep inertia: Neurophysiological and behavioural characteristics of the sleep-to-wake transition

Sleep inertia refers to the transient physiological state of hypoarousal upon awakening, associated with various degrees of impaired neurobehavioral performance, confusion, a desire to return to sleep and often a negative emotional state. Scalp and intracranial electro-encephalography as well as functional imaging studies have provided evidence that the sleep inertia phenomenon is underpinned by an heterogenous cerebral state mixing local sleep and local wake patterns of activity, at the neuronal and network levels. Sleep inertia is modulated by homeostasis and circadian processes, sleep stage upon awakening, and individual factors; this translates into a huge variability in its intensity even under physiological conditions. In sleep disorders, especially in hypersomnolence disorders such as idiopathic hypersomnia, sleep inertia may be a daily, serious and long-lasting symptom leading to severe impairment. To date, few tools have been developed to assess sleep inertia in clinical practice. They include mainly questionnaires and behavioral tests such as the psychomotor vigilance task. Only one neurophysiological protocol has been evaluated in hypersomnia, the forced awakening test which is based on an event-related potentials paradigm upon awakening. This contrasts with the major functional consequences of sleep inertia and its potentially dangerous consequences in subjects required to perform safety-critical tasks soon after awakening. There is a great need to identify reproducible biomarkers correlated with sleep inertia-associated cognitive and behavioral impairment. These biomarkers will aim at better understanding and measuring sleep inertia in physiological and pathological conditions, as well as objectively evaluating wake-promoting treatments or non-pharmacological countermeasures to reduce this phenomenon.

Non-REM Sleep Parasomnias

OBJECTIVE

Non-rapid eye movement (non-REM) parasomnias are common across the lifespan. This article describes the manifestations, diagnosis, and management of non-REM parasomnias in adults and discusses the social implications of these conditions.

LATEST DEVELOPMENTS

Non-REM parasomnias represent a hybrid state of wakefulness and sleep, often triggered by events that increase the frequency of arousals or make it more difficult to fully arouse from sleep. Sleep deprivation, certain medications, and untreated obstructive sleep apnea are known to provoke parasomnias, particularly in those who are genetically predisposed. Non-REM parasomnias include disorders of arousal (ie, sleepwalking, sleep terrors, and confusional arousals), sleep-related eating disorder, and exploding head syndrome. Clinical overlap exists between sleep-related eating disorder and disorders of arousal, suggesting that sleep-related eating disorder may be a fourth disorder of arousal or a manifestation of sleepwalking. Exploding head syndrome is a unique parasomnia of uncertain etiology.

ESSENTIAL POINTS

Non-REM parasomnias can range from minor nuisances to severe, life-altering events. While some patients with non-REM parasomnia experience significant consequences during sleep, wakefulness, or both, non-REM parasomnias do not pose a major risk to most patients. For all patients with non-REM parasomnias, safety should be explicitly discussed and addressed. Nonpharmacologic treatment should be prioritized, as increasing total sleep time, avoiding triggering substances, and treating comorbid sleep disorders is often sufficient for the management of non-REM parasomnias. If symptoms persist despite these interventions, treatment with clonazepam or other medications can be considered.

Behavioral and cognitive outcomes of habitual snoring in children aged 2-14 years in Chengdu, Sichuan

PURPOSE

Habitual snoring is associated with cognitive, behavioral, and other physiological problems of children. Few studies have reported specifically on the relationships between snoring and those problems in children as noticed by their parents. We aimed to identify the cognitive, behavioral, and sleep-related nocturnal problems in children with HS as noted by their parents.

MATERIALS AND METHODS

A cross-sectional survey was performed in Chengdu, Sichuan, China. Children aged 2-14 years from four districts were randomly chosen to participate. Questionnaires were completed voluntarily by the children's parents/guardians.

RESULTS

A total of 1548 questionnaires were analyzed and classified those children as 463 habitual snorers (HS group, 30.4 %), 683 occasional snorers (OS group, 44.8 %), and 402 non-snorers (NS group, 26.4 %). The percentages of children with sleep-related nocturnal symptoms were 94.6 %, 87.3 %, and 66.9 % in the HS, OS, and NS groups. Percentages of children with cognitive problems were 76.2 %, 74.6 %, and 64.9 % in the HS, OS, and NS groups, respectively (P < 0.001). The frequencies of daytime behavioral problems were 68.3 %, 61.5 %, and 46.8%in the HS, OS, and NS groups, respectively (P < 0.001).The average number of sleep-related nocturnal symptoms, cognitive symptoms and daytime behavioral problems was higher in the HS group than in the OS and NS groups.

CONCLUSIONS

HS is a significant contributor to sleep-related nocturnal symptoms and daytime cognitive and behavioral problems in children, as reported by their parents/guardians. HS and OS are important contributors to poor sleep quality and daytime cognitive and behavioral problems in children.

Group Cognitive Behavioural Therapy for Non-Rapid Eye Movement Parasomnias: Long-Term Outcomes and Impact of COVID-19 Lockdown

Prior to the COVID-19 pandemic, we demonstrated the efficacy of a novel Cognitive Behavioural Therapy programme for the treatment of Non-Rapid Eye Movement Parasomnias (CBT-NREMP) in reducing NREM parasomnia events, insomnia and associated mood severities. Given the increased prevalence and worsening of sleep and affective disorders during the pandemic, we examined the sustainability of CBT-NREMP following the U.K.'s longest COVID-19 lockdown (6 January 2021-19 July 2021) by repeating the investigations via a mail survey in the same 46 patient cohort, of which 12 responded. The survey included validated clinical questionnaires relating to NREM parasomnia (Paris Arousal Disorder Severity Scale), insomnia (Insomnia Severity Index) and anxiety and depression (Hospital Anxiety and Depression Scale). Patients also completed a targeted questionnaire (i.e., Impact of COVID-19 Lockdown Questionnaire, ICLQ) to assess the impact of COVID-19 lockdown on NREM parasomnia severity, mental health, general well-being and lifestyle. Clinical measures of NREM parasomnia, insomnia, anxiety and depression remained stable, with no significant changes demonstrated in questionnaire scores by comparison to the previous investigatory period prior to the COVID-19 pandemic: p (ISI) = 1.0; p (HADS) = 0.816; p (PADSS) = 0.194. These findings support the longitudinal effectiveness of CBT-NREMP for up to three years following the clinical intervention, and despite of the COVID-19 pandemic.

Violent and Complex Behaviors and Non-Restorative Sleep Are the Main Features of Disorders of Arousal in Adulthood: Real Picture or a More Severe Phenotype?

Disorders of arousal (DoA) are NREM parasomnias characterized by motor and emotional behaviors emerging from incomplete arousals from deep sleep. DoA are largely present in pediatric populations, a period during which they are labeled as self-limited manifestations. However, an extensive literature has shown that DoA can persist in adulthood, with different characteristics from childhood DoA. Adult DoA patients usually report excessive daily sleepiness, sleep-related violence during DoA episodes or potentially harmful behaviors, which are rare in childhood. The semeiological features of DoA episodes in adulthood may complicate differential diagnoses with other motor manifestations during sleep, in particular sleep-related hypermotor epilepsy. However, it cannot be excluded that adults with DoA attending sleep centers constitute a more severe phenotype, thus not being representative of adult DoA in the general population. Video-polysomnographic studies of DoA document a spectrum of motor patterns of different complexities, the simplest of which may often go unnoticed. Despite the different complexities of the episodes, neurophysiologic studies showed the co-existence of deep sleep and wakefulness during DoA episodes or even before their onset. These aspects make DoA an ideal model to investigate the mechanisms regulating local sleep, sleep arousal and cognitive functions including spatial and temporal orientation, attention or memory.

[The phenomenon of awakening from sleep and underlying neurophysiological and autonomic mechanisms]

Current research has shown that sleep is not a global process evenly covering the entire brain. The heterogeneity of wakefulness levels in different parts of the brain and differences in their activation thresholds are especially pronounced during the transitions between sleep and wakefulness. During awakening, subcortical brain structures activate first, followed by sensory and motor cortical regions, whereas the associative cortex wakes up much later. Awakening, unlike falling asleep, is not a smooth process. It begins with a short-term sharp activation of the autonomic nervous system and some wake-promoting brain regions. The amplitude of this activity burst is out of proportion to obvious physiological needs and exceeds that observed in later periods of quiet wakefulness. The review discusses the similarities and differences between awakening from sleep and hibernation in hibernating rodents. Data on some clinical consequences of impaired awakening mechanisms are also provided.

Sleep terrors-A parental nightmare

Sleep terrors (STs) are sleep disorders characterized by abrupt arousal from sleep with autonomic hyperactivity and inappropriate behavior. Though a common condition in childhood that usually affects children between 4 and 12 years of age, STs, however, may be present even in adulthood. The exact etiology of STs is not known yet, however, several hypotheses have been proposed over the years, identifying some potential genetic, neurodevelopmental, or other causes. Nevertheless, a useful pathophysiological model identified a common cascade of predisposing, priming, and precipitating factors, which could help to explain and sometimes prevent STs. Establishing a correct diagnosis is mandatory for appropriate management, as several conditions (such as other parasomnias or nocturnal seizures) may mimic STs. Furthermore, we also described some conditions which can be comorbid to STs, like some medical or psychological disorders. A number of treatment options have been proposed, ranging from only sleep hygiene practices to pharmacological therapies; we reviewed some of the most prominent ones. In spite of the fact that STs have long been considered benign disorders, which tend to reduce spontaneously over the years, they may have unexpected consequences on the child but also on the caregivers.

NonREM Disorders of Arousal and Related Parasomnias: an Updated Review

Parasomnias are abnormal behaviors and/or experiences emanating from or associated with sleep typically manifesting as motor movements of varying semiology. We discuss mainly nonrapid eye movement sleep and related parasomnias in this article. Sleepwalking (SW), sleep terrors (ST), confusional arousals, and related disorders result from an incomplete dissociation of wakefulness from nonrapid eye movement (NREM) sleep. Conditions that provoke repeated cortical arousals, and/or promote sleep inertia, lead to NREM parasomnias by impairing normal arousal mechanisms. Changes in the cyclic alternating pattern, a biomarker of arousal instability in NREM sleep, are noted in sleepwalking disorders. Sleep-related eating disorder (SRED) is characterized by a disruption of the nocturnal fast with episodes of feeding after arousal from sleep. SRED is often associated with the use of sedative-hypnotic medications, in particular the widely prescribed benzodiazepine receptor agonists. Compelling evidence suggests that nocturnal eating may in some cases be another nonmotor manifestation of Restless Legs Syndrome (RLS). Initial management should focus upon decreasing the potential for sleep-related injury followed by treating comorbid sleep disorders and eliminating incriminating drugs. Sexsomnia is a subtype of disorders of arousal, where sexual behavior emerges from partial arousal from nonREM sleep. Overlap parasomnia disorders consist of abnormal sleep-related behavior both in nonREM and REM sleep. Status dissociatus is referred to as a breakdown of the sleep architecture where an admixture of various sleep state markers is seen without any specific demarcation. Benzodiazepine therapy can be effective in controlling SW, ST, and sexsomnia, but not SRED. Paroxetine has been reported to provide benefit in some cases of ST. Topiramate, pramipexole, and sertraline can be effective in SRED. Pharmacotherapy for other parasomnias continues to be less certain, necessitating further investigation. NREM parasomnias may resolve spontaneously but require a review of priming and predisposing factors.

Sleep-Related Hypermotor Epilepsy: Etiology, Electro-Clinical Features, and Therapeutic Strategies

Sleep-related hypermotor epilepsy (SHE) is a group of clinical syndromes with heterogeneous etiologies. SHE is difficult to diagnose and treat in the early stages due to its diverse clinical manifestations and difficulties in differentiating from non-epileptic events, which seriously affect patients' quality of life and social behavior. The overall prognosis for SHE is unsatisfactory, but different etiologies affect patients' prognoses. Surgical treatment is an effective method for carefully selected patients with refractory SHE; nevertheless, preoperative assessment remains challenging because of the low sensitivity of noninvasive scalp electroencephalogram and imaging to detect abnormalities. However, through a careful analysis of semiology, the clinician can deduce the potential epileptogenic zone. This paper summarizes the research status of the background, etiology, electro-clinical features, diagnostic criteria, prognosis, and treatment of SHE to provide a more in-depth understanding of its pathophysiological mechanism, improve the accuracy in the diagnosis of this group of syndromes, and further explore more targeted therapy plans.

A Novel Group Cognitive Behavioral Therapy Approach to Adult Non-rapid Eye Movement Parasomnias

Background: Following the success of Cognitive Behavioral Therapy (CBT) for insomnia, there has been a growing recognition that similar treatment approaches might be equally beneficial for other major sleep disorders, including non-rapid eye movement (NREM) parasomnias. We have developed a novel, group-based, CBT-program for NREM parasomnias (CBT-NREMP), with the primary aim of reducing NREM parasomnia severity with relatively few treatment sessions. Methods: We investigated the effectiveness of CBT-NREMP in 46 retrospectively-identified patients, who completed five outpatient therapy sessions. The outcomes pre- and post- CBT-NREMP treatment on clinical measures of insomnia (Insomnia Severity Index), NREM parasomnias (Paris Arousal Disorders Severity Scale) and anxiety and depression (Hospital Anxiety and Depression Scale), were retrospectively collected and analyzed. In order to investigate the temporal stability of CBT-NREMP, we also assessed a subgroup of 8 patients during the 3 to 6 months follow-up period. Results: CBT-NREMP led to a reduction in clinical measures of NREM parasomnia, insomnia, and anxiety and depression severities [pre- vs. post-CBT-NREMP scores: P (Insomnia Severity Index) = 0.000054; P (Paris Arousal Disorders Severity Scale) = 0.00032; P (Hospital Anxiety and Depression Scale) = 0.037]. Improvements in clinical measures of NREM parasomnia and insomnia severities were similarly recorded for a subgroup of eight patients at follow-up, demonstrating that patients continued to improve post CBT-NREMP. Conclusion: Our findings suggest that group CBT-NREMP intervention is a safe, effective and promising treatment for NREM parasomnia, especially when precipitating and perpetuating factors are behaviorally and psychologically driven. Future randomized controlled trials are now required to robustly confirm these findings.

Eyes wide open minds shut best identify disorders of arousal in adult sleepwalkers

Grigg-Damberger M, Foldvary-Schaefer N. Eyes wide open minds shut best identify disorders of arousal in adult sleepwalkers. J Clin Sleep Med. 2020;16(1):7–8.