Idiopathic hypersomnia

Sleep architecture in idiopathic hypersomnia: the influence of age, sex, and body mass index

This study aimed to progress the understanding of idiopathic hypersomnia (IH) by assessing the moderating influence of individual characteristics, such as age, sex, and body mass index (BMI) on sleep architecture. In this retrospective study, 76 IH participants (38.1 ± 11.3 years; 40 women) underwent a clinical interview, an in-laboratory polysomnography with a maximal 9-h time in bed and a multiple sleep latency test (MSLT). They were compared to 106 healthy controls (38.1 ± 14.1 years; 60 women). Multiple regressions were used to assess moderating influence of age, sex, and BMI on sleep variables. We used correlations to assess whether sleep variables were associated with Epworth Sleepiness Scale scores and mean sleep onset latency on the MSLT in IH participants. Compared to controls, IH participants had shorter sleep latency (p = 0.002), longer total sleep time (p < 0.001), more time spent in N2 sleep (p = 0.008), and showed trends for a higher sleep efficiency (p = 0.023) and more time spent in rapid eye movement (REM) sleep (p = 0.022). No significant moderating influence of age, sex, or BMI was found. More severe self-reported sleepiness in IH patients was correlated with shorter REM sleep latency and less N1 sleep in terms of proportion and duration (ps < 0.01). This study shows that, when compared to healthy controls, patients with IH had no anomalies in their sleep architecture that can explain their excessive daytime sleepiness. Moreover, there is no moderating influence of age, sex, and BMI, suggesting that the absence of major group differences is relatively robust.

Clinical considerations in the treatment of idiopathic hypersomnia

Idiopathic hypersomnia typically is a chronic and potentially debilitating neurologic sleep disorder, and is characterized by excessive daytime sleepiness. In addition to excessive daytime sleepiness, idiopathic hypersomnia symptoms can include severe sleep inertia; long, unrefreshing naps; long sleep time; and cognitive dysfunction. Patients with idiopathic hypersomnia may experience a significant impact on their quality of life, work or school performance, earnings, employment, and overall health. Given the complex range of symptoms associated with idiopathic hypersomnia and the array of treatments available, there is a need to provide guidance on the treatment of idiopathic hypersomnia and the clinically relevant recommendations that enhance effective disease management. Identifying appropriate treatment options for idiopathic hypersomnia requires timely and accurate diagnosis, consideration of individual patient factors, and frequent reassessment of symptom severity. In 2021, low-sodium oxybate was the first treatment to receive approval by the US Food and Drug Administration for the treatment of idiopathic hypersomnia in adults. However, many off-label treatments continue to be used. Adjunct nonpharmacologic therapies, including good sleep hygiene, patient education and counseling, and use of support groups, should be recognized and recommended when appropriate. This narrative review describes optimal treatment strategies that take into account patient-specific factors, as well as the unique characteristics of each medication and the evolution of a patient's response to treatment. Perspectives on appropriate symptom measurement and management, and potential future therapies, are also offered.

The nature and magnitude of cognitive impairment in narcolepsy type 1, narcolepsy type 2, and idiopathic hypersomnia: a meta-analysis

People with narcolepsy type 1 (NT1), narcolepsy type 2 (NT2), and idiopathic hypersomnia (IH) often report cognitive impairment which can be quite burdensome but is rarely evaluated in routine clinical practice. In this systematic review and meta-analysis, we assessed the nature and magnitude of cognitive impairment in NT1, NT2, and IH in studies conducted from January 2000 to October 2022. We classified cognitive tests assessing memory, executive function, and attention by cognitive domain. Between-group differences were analyzed as standardized mean differences (Cohen's d), and Cohen's d for individual tests were integrated according to cognitive domain and clinical disease group. Eighty-seven studies were screened for inclusion; 39 satisfied inclusion criteria, yielding 73 comparisons (k): NT1, k = 60; NT2, k = 8; IH, k = 5. Attention showed large impairment in people with NT1 (d = -0.90) and IH (d = -0.97), and moderate impairment in NT2 (d = -0.60). Executive function was moderately impaired in NT1 (d = -0.30) and NT2 (d = -0.38), and memory showed small impairments in NT1 (d = -0.33). A secondary meta-analysis identified sustained attention as the most impaired domain in NT1, NT2, and IH (d ≈ -0.5 to -1). These meta-analyses confirm that cognitive impairments are present in NT1, NT2, and IH, and provide quantitative confirmation of reports of cognitive difficulties made by patients and clinicians. These findings provide a basis for the future design of studies to determine whether cognitive impairments can improve with pharmacologic and nonpharmacologic treatments for narcolepsy and IH.

Sleep disorders in a naturalistic cohort of Dutch psychiatric outpatients: prevalence rates and associations with psychopathology symptom severity and well-being

Sleep problems are very common in individuals with a mental disorder. Given the abundant evidence indicating the negative impact of disturbed sleep on mental health outcome, insight into the prevalence of all types of sleep disorders in specific mental disorders and neurodevelopmental conditions is of practical importance. Therefore, we estimated the prevalence of six types of sleep disorders with the Holland Sleep Disorders Questionnaire in an overall mental health sample (n = 1082) and separately for different mental and neurodevelopmental conditions. Furthermore, associations between specific sleep disorders, psychopathology and well-being were studied. The impact of the total number of sleep disorders on these associations was examined. Overall, 46.2% of all participants scored above the cut-off for having a sleep disorder. Specifically, 26.8% scored on insomnia, 12.1% on sleep breathing disorders, 9.7% on hypersomnia, 13.7% on circadian rhythm sleep-wake disorders, 11.2% on parasomnia, and 17.9% on sleep-related movement disorders. Most sleep disorders were associated with greater severity of psychopathology and lower well-being. These associations got stronger with an increasing number of sleep disorders. Our study revealed higher suspected prevalence of most sleep disorders in a mental disorder sample compared to the general population. Moreover, the presence of sleep disorder(s) was strongly associated with symptom severity and reduced well-being. These findings extend the notion that early detection and treatment of sleep disorders in mental health populations is essential for psychiatric outcome.

Pupillometry to differentiate idiopathic hypersomnia from narcolepsy type 1

Idiopathic hypersomnia is poorly diagnosed in the absence of biomarkers to distinguish it from other central hypersomnia subtypes. Given that light plays a main role in the regulation of sleep and wake, we explored the retinal melanopsin-based pupil response in patients with idiopathic hypersomnia and narcolepsy type 1, and healthy subjects. Twenty-seven patients with narcolepsy type 1 (women 59%, 36 ± 11.5 years old), 36 patients with idiopathic hypersomnia (women 83%, 27.2 ± 7.2 years old) with long total sleep time (> 11/24 hr), and 43 controls (women 58%, 30.6 ± 9.3 years old) were included in this study. All underwent a pupillometry protocol to assess pupil diameter, and the relative post-illumination pupil response to assess melanopsin-driven pupil responses in the light non-visual input pathway. Differences between groups were assessed using logistic regressions adjusted on age and sex. We found that patients with narcolepsy type 1 had a smaller baseline pupil diameter as compared with idiopathic hypersomnia and controls (p < 0.05). In addition, both narcolepsy type 1 and idiopathic hypersomnia groups had a smaller relative post-illumination pupil response (respectively, 31.6 ± 13.9% and 33.2 ± 9.9%) as compared with controls (38.7 ± 9.7%), suggesting a reduced melanopsin-mediated pupil response in both types of central hypersomnia (p < 0.01). Both narcolepsy type 1 and idiopathic hypersomnia showed a smaller melanopsin-mediated pupil response, and narcolepsy type 1, unlike idiopathic hypersomnia, also displayed a smaller basal pupil diameter. Importantly, we found that the basal pupil size permitted to well discriminate idiopathic hypersomnia from narcolepsy type 1 with a specificity = 66.67% and a sensitivity = 72.22%. Pupillometry may aid to multi-feature differentiation of central hypersomnia subtypes.

Sleepiness in neurological disorders

Sleepiness is a frequent and underrecognized symptom in neurological disorders, that impacts functional outcomes and quality of life. Multiple and potentially additive factors might contribute to sleepiness in neurological disorders, including sleep quality alterations, circadian rhythm disorders, drugs, and sleep disorders including sleep apnea or central disorders of hypersomnolence. Physician awareness of the possible symptoms of hypersomnolence, and associated causes is of crucial importance to allow proper identification and treatment of underlying causes. This review first provides a brief overview on clinical aspects of excessive daytime sleepiness, and diagnosis tools, then examines its frequency and mechanisms in various neurological disorders, including neurodegenerative disorders, multiple sclerosis, autoimmune encephalitis, epilepsy, and stroke.

Long-Term Treatment of Narcolepsy and Idiopathic Hypersomnia with Low-Sodium Oxybate

Narcolepsy and idiopathic hypersomnia are chronic conditions that negatively affect alertness, mental and physical energy, functioning, and quality of life (QoL). Calcium, magnesium, potassium, and sodium oxybates (low-sodium oxybate; LXB) is an oxybate formulation with 92% less sodium than sodium oxybate (SXB; a treatment for narcolepsy) and the same active moiety. LXB is approved in the US for treatment of cataplexy or excessive daytime sleepiness (EDS) in patients 7 years of age or older with narcolepsy, and idiopathic hypersomnia in adults. In Phase 3 clinical trials, LXB exhibited a safety profile consistent with that of SXB in narcolepsy. Besides continued efficacy in treating symptoms, potential benefits of long-term LXB treatment include flexible optimization of dosing and regimen, improvement of QoL and functioning, weight loss, and (relative to SXB in narcolepsy) health benefits of reduced sodium content. Dosing of LXB is twice nightly (for narcolepsy) or once or twice nightly (for idiopathic hypersomnia) based on patient characteristics and response, and individualized titration can be leveraged over the long term as a patient's life circumstances change. Patients with narcolepsy transitioning from SXB initiate LXB at the same dose, and most patients require no further changes to achieve similar efficacy and tolerability. Improvements in functioning and QoL with LXB treatment could have cascading positive effects in multiple domains, particularly in younger patients. In clinical trials, LXB was associated with weight loss in both narcolepsy (in which obesity is a well-established comorbidity) and idiopathic hypersomnia, only occasionally leading participants to be underweight. As both narcolepsy and idiopathic hypersomnia are associated with increased risk of cardiometabolic and cardiovascular comorbidities, limiting medication-related sodium intake with LXB may have significant health benefits, although this has not yet been verified prospectively due to the prolonged follow-up required. LXB is a promising long-term treatment for narcolepsy and idiopathic hypersomnia.

Impairment in Functioning and Quality of Life in Patients with Idiopathic Hypersomnia: The Real World Idiopathic Hypersomnia Outcomes Study (ARISE)

Purpose

Idiopathic hypersomnia is a debilitating neurologic sleep disorder characterized by excessive daytime sleepiness, sleep inertia, and prolonged sleep. Its impact on patients' quality of life and daily functioning has not been fully elucidated. The Real World Idiopathic Hypersomnia Outcomes Study (ARISE) evaluated the daily functioning, relationships, cognition, emotional well-being, and productivity/employment of participants with idiopathic hypersomnia.

Patients and Methods

ARISE was a US-based virtual cross-sectional survey comprising multiple patient-reported outcome measures (Functional Outcomes of Sleep Questionnaire, short version [FOSQ-10], Quality of Life in Neurological Disorders [Neuro-QoL] Social Roles and Stigma domains, British Columbia Cognitive Complaints Inventory [BC-CCI], Patient Health Questionnaire [PHQ-9], and the Work Productivity and Activity Impairment Questionnaire: Specific Health Problem [WPAI:SHP]). Participants were adults 21-65 years of age with idiopathic hypersomnia. Data were analyzed for all participants and for subgroups with/without long sleep time (LST; self-reported sleep ≥11 hours in 24 hours).

Results

Of 75 participants enrolled, most were female (81.3%) and the mean (SD) age was 34.1 (10.7) years. Participants' scores on the FOSQ-10 (mean [SD] score: 10.7 [2.8]) and the Neuro-QoL Social Roles (43.4 [4.2]) and Stigma (57.3 [5.9]) domains reflected impairments in daily functioning and quality of life. More than half of participants reported moderate to severe cognitive complaints (BC-CCI; 62.7%) and moderate to severe depressive symptoms (PHQ-9; 66.7%). Scores on the WPAI:SHP showed substantial impairments in absenteeism, presenteeism, overall work productivity, and overall regular daily activity (mean percent [SD]: 12.3 [23.6], 47.6 [22.7], 51.4 [24.7], and 64.0 [21.9], respectively). These considerable impairments were found in participants with and without LST.

Conclusion

ARISE participants with idiopathic hypersomnia demonstrated poor quality of life and impaired functioning across multiple symptom domains.

Face validation and pharmacologic analysis of Sik3Sleepy mutant mouse as a possible model of idiopathic hypersomnia

Idiopathic hypersomnia (IH) is a chronic neurologic disorder with unknown mechanisms that result in long night-time sleep, daytime sleepiness, long non-refreshing naps, and difficult awakening presenting as sleep drunkenness. IH patients are typically diagnosed by shorter sleep latency on multiple sleep latency test (MSLT) along with long sleep time. Only symptomatic drug treatments are currently available for IH and no animal model to study it. Sleepy mice carry a splicing mutation in the Sik3 gene, leading to increased sleep time and sleep need. Here we used a mouse version of MSLT and a decay analysis of wake EEG delta power to validate the Sleepy mutant mouse as an animal model for IH. Sleepy mice had shorter sleep latency in the dark (active) phase than wild-type mice. They also showed lower decay of EEG delta density during wakefulness, possibly reflecting increased sleep inertia. These data indicate that the Sleepy mouse may have partial face validity as a mouse model for idiopathic hypersomnia. We then investigated the effect of orexin-A and the orexin receptor 2-selective agonist YNT-185 on the sleepiness symptoms of the Sleepy mouse. Intracerebroventricular orexin-A promoted wakefulness for 3 h and decreased wake EEG delta density after injection in Sleepy mice and wild-type mice. Moreover, Sleepy mice but not wild-type mice showed a sleep rebound after the orexin-A-induced wakefulness. Intraperitoneal YNT-185 promoted wakefulness for 3 h after injection in Sleepy mice, indicating the potential of using orexin agonists to treat not only orexin deficiency but hypersomnolence of various etiologies.

Differences in psychosocial factors and sleep study findings between delayed sleep-wake phase disorder and hypersomnia in teenagers

Central hypersomnia (HS) and delayed sleep-wake phase disorder (DSWPD) appear commonly in adolescents, and they severely reduce quality of life and have an enormous impact on academic performance and other aspects of development. Although these disorders are thought to be considerably different in etiology, it is sometimes difficult to distinguish them because of their similar clinical features. This study aimed to compare psychosocial factors and sleep study findings between HS and DSWPD in teenagers. The clinical data of 89 teenagers who visited the psychiatric section of the Sleep Medicine Center of Nihon University Itabashi Hospital from January 2013 to December 2019 were analyzed. Psychosocial factors were evaluated at the first visit, and polysomnography (PSG) and the multiple sleep latency test (MSLT) were performed for patients deemed to require definitive diagnosis. Compared with patients with HS, those with DSWPD had a higher rate of mother's employment, introversion, adjustment problems, events that triggered the disorder, concurrent mental disorders, habitual lateness, and difficulty attending school or work. PSG did not show any differences in sleep parameters between the two disorders, except for sleep latency. On the MSLT, sleep latency was shorter in those with HS on the second, third, and fourth tests. The present results suggest that focusing on psychosocial factors could be useful for differential diagnosis of the two disorders that appear commonly in adolescents.

Multiple Sleep Latency Test/Maintenance of Wakefulness Test and Central Hypersomnias: Evolving Diagnostic and Therapeutic Approaches

SUMMARY

Central disorders of hypersomnolence include a spectrum of conditions, such as narcolepsy, idiopathic hypersomnia, and Kleine-Levin syndrome, in which excessive daytime sleepiness is the primary feature. Subjective testing with tools, such as sleep logs and sleepiness scales, are often helpful in the evaluation of these disorders but do not necessarily correlate well with objective testing, such as polysomnography and multiple sleep latency test and maintenance of wakefulness test. The most recent International Classification of Sleep Disorders-Third Edition has incorporated biomarkers, such as cerebrospinal fluid hypocretin level, into the diagnostic criteria and have restructured the classification of conditions based on our evolved understanding of their underlying pathophysiologic mechanisms. Therapeutic approaches largely consist of behavioral therapy, with a focus on optimizing sleep hygiene, optimizing opportunity for sleep, and strategic napping, along with judicious use of analeptic and anticataleptic agents when necessary. Emerging therapy has revolved around hypocretin-replacement therapy, immunotherapy, and nonhypocretin agents, with the goal of better targeting the underlying pathophysiology of these disorders rather than addressing symptoms. The most novel treatments have targeted the histaminergic system (pitolisant), dopamine reuptake transmission (solriamfetol), and gamma-aminobutyric acid modulation (flumazenil and clarithromycin) to promote wakefulness. Continued research is required for a more solid understanding of the biology of these conditions to develop a more robust armamentarium of therapeutic options.

Update on the treatment of idiopathic hypersomnia: Progress, challenges, and expert opinion

Idiopathic hypersomnia is a central hypersomnolence disorder of unknown origin characterized by excessive daytime sleepiness despite normal or long sleep time, and frequent severe sleep inertia. Management strategies have been largely derived from expert consensus, due to a lack of disease-specific assessments and reliance on case series and rare randomized controlled studies. Guidelines recommend treatment with off-label medications. Modafinil, which was approved for idiopathic hypersomnia until 2011 in Europe, is the most commonly used treatment and improved sleepiness in two recent randomized placebo-controlled trials. In 2021, low-sodium oxybate (LXB) was approved in the United States for idiopathic hypersomnia. In a placebo-controlled, double-blind, randomized withdrawal study, LXB reduced daytime sleepiness and sleep inertia, and improved daily functioning. Here, treatment options are reviewed considering the authors' professional experience, current guidelines, and the latest research developments. The choice of pharmacotherapy should be guided by symptom profile, age, comorbidities (eg, depressive symptoms, cardiovascular problems), and concomitant medications (eg, oral contraceptives). Nonpharmacologic approaches have a role in management. An instrument (idiopathic hypersomnia severity scale) has been validated in idiopathic hypersomnia specifically, opening a path to better assessment of symptoms, impact, and response to treatment. Continued research on idiopathic hypersomnia is needed to support treatment algorithms.

Rapid eye movement sleep duration during the multiple sleep latency test to diagnose hypocretin-deficient narcolepsy

STUDY OBJECTIVES

To assess the performances of alternative measures of the multiple sleep latency test (MSLT) to identify hypocretin-deficiency in patients with a complaint of hypersomnolence, including patients with narcolepsy.

METHODS

MSLT parameters from 374 drug-free patients with hypersomnolence, with complete clinical and polysomnographic (PSG) assessment and cerebrospinal hypocretin-1 measurement were collected. Conventional (sleep latency, number of sleep onset REM-SOREM-periods) and alternative (sleep duration, REM sleep latency and duration, sleep stage transitions) MSLT measures were compared as function of hypocretin-1 levels (≤110 vs > 110 pg/mL). We performed receiver-operating characteristics analyses to determine the best thresholds of MSLT parameters to identify hypocretin-deficiency in the global population and in subgroups of patients with narcolepsy (i.e. typical cataplexy and/or positive PSG/MSLT criteria, n = 223).

RESULTS

Patients with hypocretin-deficiency had shorter mean sleep and REM sleep latencies, longer mean sleep and REM sleep durations and more direct REM sleep transitions during the MSLT. The current standards of MSLT/PSG criteria identified hypocretin-deficient patients with a sensitivity of 0.87 and a specificity of 0.69, and 0.81/0.99 when combined with cataplexy. A mean REM sleep duration ≥ 4.1 min best identified hypocretin-deficiency in patients with hypersomnolence (AUC = 0.932, sensitivity 0.87, specificity 0.86) and ≥ 5.7 min in patients with narcolepsy (AUC = 0.832, sensitivity 0.77, specificity 0.82).

CONCLUSION

Compared to the current neurophysiological standard criteria, alternative MSLT parameters would better identify hypocretin-deficiency among patients with hypersomnolence and those with narcolepsy. We highlighted daytime REM sleep duration as a relevant neurophysiological biomarker of hypocretin-deficiency to be used in clinical and research settings.

Symptom Severity and Treatment Satisfaction in Patients with Idiopathic Hypersomnia: The Real World Idiopathic Hypersomnia Outcomes Study (ARISE)

Objective

Idiopathic hypersomnia is a debilitating sleep disorder characterized by excessive daytime sleepiness, sleep inertia, and prolonged sleep duration. The patient burden of idiopathic hypersomnia is poorly understood. The Real World Idiopathic Hypersomnia Outcomes Study (ARISE) evaluated symptoms and treatment effectiveness/satisfaction in participants with idiopathic hypersomnia.

Methods

ARISE was a United States-based virtual cross-sectional survey. Participants were adults 21-65 years of age with idiopathic hypersomnia recruited from social media, the Hypersomnia Foundation website, and a patient panel. Self-assessments included the Epworth Sleepiness Scale (ESS), Idiopathic Hypersomnia Severity Scale (IHSS), Treatment Satisfaction Questionnaire for Medication, version II (TSQM-vII), and additional treatment questions. Data were analyzed for all participants and for subgroups with/without long sleep time (LST; ≥11 hours in 24 hours).

Results

Of 75 participants enrolled, most were female (81.3%). The mean (SD) age was 34.1 (10.7) years and 49% had LST. Most participants took off-label prescription medications (89.3%) and/or used other measures (93.3%) to manage their symptoms. The mean (SD) ESS score was 14.5 (3.5) and the mean IHSS score was 35.2 (7.6). Treatment satisfaction was low (mean [SD] TSQM-vII score: overall, 61.9 [21.2]; with LST, 57.9 [21.4]; without LST, 66.7 [20.3]), primarily driven by dissatisfaction with treatment effectiveness. The most common classes of prescription medications used were stimulants (61.3%), wake-promoting agents (28.0%), and antidepressants (18.7%); non-prescription measures used to manage symptoms included caffeine (73.3%), planned naps (34.7%), and individual accommodations (32.0%).

Conclusion

Overall, participants with idiopathic hypersomnia, with or without LST, had substantial symptom burden despite most of the study population taking off-label medications and using nonprescription measures to manage symptoms.

Clinical considerations for the diagnosis of idiopathic hypersomnia

Idiopathic hypersomnia is a sleep disorder of neurologic origin characterized by excessive daytime sleepiness, with sleep inertia, long, unrefreshing naps, and prolonged nighttime sleep being key symptoms in many patients. Idiopathic hypersomnia is described in the International Classification of Sleep Disorders, 3rd Edition as a central disorder of hypersomnolence with distinct clinical features and diagnostic criteria; however, confirming the diagnosis of idiopathic hypersomnia is often challenging. Diagnosis of idiopathic hypersomnia is based on objective sleep testing and the presence of associated clinical features but may be difficult for clinicians to recognize and correctly diagnose because of its low prevalence, clinical heterogeneity, and symptoms, which are similar to those of other sleep disorders. The testing required for diagnosis of idiopathic hypersomnia also presents logistical barriers, and reliability of objective sleep measures is suboptimal. The pathophysiology of idiopathic hypersomnia remains unknown. In this review, clinical considerations related to the pathogenesis, diagnosis, and management of idiopathic hypersomnia will be discussed, including perspectives from the European Union and United States.

Pharmacologic Management of Excessive Daytime Sleepiness

Excessive daytime sleepiness (EDS) is defined as "irresistible sleepiness in a situation when an individual would be expected to be awake, and alert." EDS has been a big concern not only from a medical but also from a public health point of view. Patients with EDS have the possibility of falling asleep even when they should wake up and concentrate, for example, when they drive, play sports, or walk outside. In this article, clinical characteristics of common hypersomnia and pharmacologic treatments of each hypersomnia are described.

Impairment of executive functions due to sleep alterations: An integrative review on the use of P300

Objective

Cognitive impairment due to sleep deprivation (SD) is an important global health concern as part of the growing rates of sleep disorders and sleep deprivation worldwide. Amongst the affected cognitive processes, the effects of SD on the executive functions (EFs) show diverse methods and inconclusive or contradictory results, highlighting the importance of further research in this field. Considering this scenario, we evaluate one of the most used methods for objectively evaluating EFs on SD: the event-related potential (ERP) P300.

Methods

Our study provides a comprehensive review on the use of P300 for evaluating executive functions in sleep alterations on subjects of all ages, as well as an analysis on the efficiency of P300 as an assessment method for executive functions compared to traditional neurocognitive batteries. We review the benefits of P300 application for multiple sleep/wake alterations, whether evoked in laboratory or as part of pre-existing sleep disorders.

Results

We assess the diverse protocols used to elicit and complement P300, the most identified alterations in amplitude and latency, and suggest new lines of study that could benefit from P300 within the field.

Conclusion

We conclude that P300 is a valuable asset for evaluating executive dysfunction under sleep deprivation both as a standalone protocol and in conjunction with subjective methods, with consistently significant results in assessing executive dysfunction in a diversity of subjects and etiologies.

Idiopathic Hypersomnia-A Dynamic Simulation Model

Aims of the study

Commonly used approach to illness assessment focuses on the patient's actual state supplemented by binary records of past events and conditions. This research project was designed to explain subjective experience in idiopathic hypersomnia (IH) patients influenced by their clinical symptoms and comorbidities.

Material and Methods

Forty-three IH patients of both sexes (female 60.5%, male 39.5%) were assessed using a detailed structured examination. The interview covered neurologic, psychiatric, and internal medicine anamnesis, medication past and current, substance abuse, work impairment, detailed sleep-related data, specific sleep medication, and a full-length set of questionnaires including depression, quality of life, sleepiness, anxiety, fatigue, insomnia, and sleep inertia. The data were digitized and imported into statistical software (SPSS by IBM), and dynamic simulation software (Vensim by Ventana Systems Inc.) was used to build a causal loop diagram and stocks and flows diagram as a simulation structure.

Results

The overall raw data and simulation-based patterns fit at 76.1%. The simulation results also identified the parameters that contribute the most to patients' subjective experience. These included sleep inertia, the refreshing potential of naps, the quality of nocturnal sleep, and the social aspects of the patient's life. Psychiatric disorders influence the overall pattern at a surprisingly low level. The influence of medication has been studied in detail. Although its contribution to the dynamics looks marginal at first sight, it significantly influences the contribution of other variables to the overall patient experience of the disease.

Conclusion

Even the simplified dynamic structure designed by the research team reflects the real-life events in patients with IH at the acceptable level of 76.1% and suggests that a similar structure plays an important role in the course of the disease. Therapeutic focus on the parameters identified by the model should enhance the patients' subjective experience throughout illness duration and might even turn the progress from negative into positive. Further research is needed to understand the dynamics of idiopathic hypersomnia in greater detail to better understand the causes and design therapeutic approaches to improve patients' quality of life.

Data-Driven Phenotyping of Central Disorders of Hypersomnolence With Unsupervised Clustering

BACKGROUND AND OBJECTIVES

Recent studies fueled doubts as to whether all currently defined central disorders of hypersomnolence are stable entities, especially narcolepsy type 2 and idiopathic hypersomnia. New reliable biomarkers are needed, and the question arises of whether current diagnostic criteria of hypersomnolence disorders should be reassessed. The main aim of this data-driven observational study was to see whether data-driven algorithms would segregate narcolepsy type 1 and identify more reliable subgrouping of individuals without cataplexy with new clinical biomarkers.

METHODS

We used agglomerative hierarchical clustering, an unsupervised machine learning algorithm, to identify distinct hypersomnolence clusters in the large-scale European Narcolepsy Network database. We included 97 variables, covering all aspects of central hypersomnolence disorders such as symptoms, demographics, objective and subjective sleep measures, and laboratory biomarkers. We specifically focused on subgrouping of patients without cataplexy. The number of clusters was chosen to be the minimal number for which patients without cataplexy were put in distinct groups.

RESULTS

We included 1,078 unmedicated adolescents and adults. Seven clusters were identified, of which 4 clusters included predominantly individuals with cataplexy. The 2 most distinct clusters consisted of 158 and 157 patients, were dominated by those without cataplexy, and among other variables, significantly differed in presence of sleep drunkenness, subjective difficulty awakening, and weekend-week sleep length difference. Patients formally diagnosed as having narcolepsy type 2 and idiopathic hypersomnia were evenly mixed in these 2 clusters.

DISCUSSION

Using a data-driven approach in the largest study on central disorders of hypersomnolence to date, our study identified distinct patient subgroups within the central disorders of hypersomnolence population. Our results contest inclusion of sleep-onset REM periods in diagnostic criteria for people without cataplexy and provide promising new variables for reliable diagnostic categories that better resemble different patient phenotypes. Cluster-guided classification will result in a more solid hypersomnolence classification system that is less vulnerable to instability of single features.

The melanopsin-mediated pupil response is reduced in idiopathic hypersomnia with long sleep time

Idiopathic hypersomnia (IH), characterized by an excessive day-time sleepiness, a prolonged total sleep time on 24 h and/or a reduced sleep latency, affects 1 in 2000 individuals from the general population. However, IH remains underdiagnosed and inaccurately treated despite colossal social, professional and personal impacts. The pathogenesis of IH is poorly known, but recent works have suggested possible alterations of phototransduction. In this context, to identify biomarkers of IH, we studied the Post-Illumination Pupil Response (PIPR) using a specific pupillometry protocol reflecting the melanopsin-mediated pupil response in IH patients with prolonged total sleep time (TST > 660 min) and in healthy subjects. Twenty-eight patients with IH (women 86%, 25.4 year-old ± 4.9) and 29 controls (women 52%, 27.1 year-old ± 3.9) were included. After correction on baseline pupil diameter, the PIPR was compared between groups and correlated to sociodemographic and sleep parameters. We found that patients with IH had a lower relative PIPR compared to controls (32.6 ± 9.9% vs 38.5 ± 10.2%, p = 0.037) suggesting a reduced melanopsin response. In addition, the PIPR was not correlated to age, chronotype, TST, nor depressive symptoms. The melanopsin-specific PIPR may be an innovative trait marker of IH and the pupillometry might be a promising tool to better characterize hypersomnia.

A rare genetic variant in the cleavage site of prepro-orexin is associated with idiopathic hypersomnia

Idiopathic hypersomnia (IH) is a rare, heterogeneous sleep disorder characterized by excessive daytime sleepiness. In contrast to narcolepsy type 1, which is a well-defined type of central disorders of hypersomnolence, the etiology of IH is poorly understood. No susceptibility loci associated with IH have been clearly identified, despite the tendency for familial aggregation of IH. We performed a variation screening of the prepro-orexin/hypocretin and orexin receptors genes and an association study for IH in a Japanese population, with replication (598 patients and 9826 controls). We identified a rare missense variant (g.42184347T>C; p.Lys68Arg; rs537376938) in the cleavage site of prepro-orexin that was associated with IH (minor allele frequency of 1.67% in cases versus 0.32% in controls, P = 2.7 × 10-8, odds ratio = 5.36). Two forms of orexin (orexin-A and -B) are generated from cleavage of one precursor peptide, prepro-orexin. The difference in cleavage efficiency between wild-type (Gly-Lys-Arg; GKR) and mutant (Gly-Arg-Arg; GRR) peptides was examined by assays using proprotein convertase subtilisin/kexin (PCSK) type 1 and PCSK type 2. In both PCSK1 and PCSK2 assays, the cleavage efficiency of the mutant peptide was lower than that of the wild-type peptide. We also confirmed that the prepro-orexin peptides themselves transmitted less signaling through orexin receptors than mature orexin-A and orexin-B peptides. These results indicate that a subgroup of IH is associated with decreased orexin signaling, which is believed to be a hallmark of narcolepsy type 1.

Idiopathic Hypersomnia: Historical Account, Critical Review of Current Tests and Criteria, Diagnostic Evaluation in the Absence of Biological Markers and Robust Electrophysiological Diagnostic Criteria

Idiopathic hypersomnia was first described in 1976 under two forms: polysymptomatic, characterized by excessive daytime sleepiness, long and unrefreshing naps, nocturnal sleep of abnormally long duration and signs of sleep drunkenness upon awakening; monosymptomatic, manifested by excessive daytime sleepiness only. Yet, after 45 years, this sleep disorder is still poorly delineated and diagnostic criteria produced by successive International Classifications of Sleep Disorders are far from satisfactory. The first part of this review is a historical account of the successive names and descriptions of idiopathic hypersomnia: monosymptomatic and polysymptomatic idiopathic hypersomnia in 1976; central nervous system idiopathic hypersomnia in 1979; idiopathic hypersomnia in 1990; idiopathic hypersomnia with and without long sleep time in 2005; idiopathic hypersomnia again in 2014; and, within the last few years, the proposal of separating idiopathic hypersomnia into a well-defined subtype, idiopathic hypersomnia with long sleep duration, and a more heterogeneous subtype combining idiopathic hypersomnia without long sleep duration and narcolepsy type 2. The second part is a critical review of both current ICSD-3 diagnostic criteria and clinical features, scales and questionnaires, electrophysiological and circadian control tests, research techniques, currently used to diagnose idiopathic hypersomnia. The third part proposes a diagnostic evaluation of idiopathic hypersomnia, in the absence of biologic markers and of robust electrophysiological diagnostic criteria.

Idiopathic Hypersomnia Severity Scale to better quantify symptoms severity and their consequences in idiopathic hypersomnia

STUDY OBJECTIVES

To assess the responsiveness of the Idiopathic Hypersomnia Severity Scale (IHSS) to medications and estimate the minimum clinically important difference, to report clinically relevant score ranges, and to confirm its psychometric properties and whether items need to be weighted in drug-free and treated patients with idiopathic hypersomnia (IH).

METHODS

Two-hundred twenty-six (166 drug-free and 60 treated) patients with IH (cross-sectional sample) completed the 14-item IHSS to quantify the severity of the 3 major IH symptoms (excessive daytime sleepiness, prolonged nighttime sleep, and sleep inertia) and consequences; 77 untreated patients were evaluated again after treatment (longitudinal sample). Patients filled in the Epworth Sleepiness Scale, Beck Depression Inventory II, and European Quality of Life questionnaires.

RESULTS

The IHSS confirmed adequate psychometric properties with a factor analysis indicating a 3-component solution. IHSS total score was lower in treated than untreated patients, with a mean difference of 4-5 points in the cross-sectional and longitudinal samples. Distribution-based methods were used to estimate that 4 points represented the minimum clinically important difference. Four severity levels were defined with between-group differences related to treatment. The probability of having severe sleepiness, depressive symptoms, and low quality of life increased with the severity level. Our results showed that IHSS item-weighting was not necessary.

CONCLUSIONS

The IHSS is a valid and reliable tool to quantify IH symptoms, with 4 severity score levels of clinical importance. The IHSS has adequate psychometric properties and can detect symptom changes after treatment. These findings should stimulate its use in clinical settings and in research studies.

CITATION

Rassu AL, Evangelista E, Barateau L, et al. Idiopathic Hypersomnia Severity Scale to better quantify symptoms severity and their consequences in idiopathic hypersomnia. J Clin Sleep Med. 2022;18(2):617-629.

Genome-wide association study of idiopathic hypersomnia in a Japanese population

Idiopathic hypersomnia (IH) is a rare sleep disorder characterized by excessive daytime sleepiness, great difficulty upon awakening, and prolonged sleep time. In contrast to narcolepsy type 1, which is a well-recognized hypersomnia, the etiology of IH remains poorly understood. No susceptibility loci for IH have been identified, although familial aggregations have been observed among patients with IH. Narcolepsy type 1 is strongly associated with human leukocyte antigen (HLA)-DQB1*06:02; however, no significant associations between IH and HLA alleles have been reported. To identify genetic variants that affect susceptibility to IH, we performed a genome-wide association study (GWAS) and two replication studies involving a total of 414 Japanese patients with IH and 6587 healthy Japanese individuals. A meta-analysis of the three studies found no single-nucleotide polymorphisms (SNPs) that reached the genome-wide significance level. However, we identified several candidate SNPs for IH. For instance, a common genetic variant (rs2250870) within an intron of PDE9A was suggestively associated with IH. rs2250870 was significantly associated with expression levels of PDE9A in not only whole blood but also brain tissues. The leading SNP in the PDE9A region was the same in associations with both IH and PDE9A expression. PDE9A is a potential target in the treatment of several brain diseases, such as depression, schizophrenia, and Alzheimer's disease. It will be necessary to examine whether PDE9A inhibitors that have demonstrated effects on neurophysiologic and cognitive function can contribute to the development of new treatments for IH, as higher expression levels of PDE9A were observed with regard to the risk allele of rs2250870. The present study constitutes the first GWAS of genetic variants associated with IH. A larger replication study will be required to confirm these associations.

Supplementary Information

The online version contains supplementary material available at 10.1007/s41105-021-00349-2.

Efficacy and Safety of Lower-Sodium Oxybate in an Open-Label Titration Period of a Phase 3 Clinical Study in Adults with Idiopathic Hypersomnia

PURPOSE

To report the efficacy and safety of lower-sodium oxybate (LXB; Xywav^®) during the open-label titration and optimization period (OLT) and stable-dose period (SDP) in a clinical study for the treatment of idiopathic hypersomnia.

PATIENTS AND METHODS

Data were collected during treatment titration and optimization in a phase 3 randomized withdrawal trial in adults (18-75 years of age) with idiopathic hypersomnia who took LXB treatment (once, twice, or thrice nightly, administered orally) in the OLT (10-14 weeks), followed by the 2-week, open-label SDP. Endpoints included the Epworth Sleepiness Scale (ESS), Idiopathic Hypersomnia Severity Scale (IHSS), Patient Global Impression of Change, Clinical Global Impression of Change, Functional Outcomes of Sleep Questionnaire (FOSQ)-10, and Work Productivity and Activity Impairment Questionnaire: Specific Health Problem (WPAI:SHP).

RESULTS

The safety population included 154 participants; the modified intent-to-treat population comprised 115 participants. During open-label treatment, mean (SD) ESS scores improved (decreased) from 15.7 (3.8) at baseline to 6.1 (4.0) at end of SDP, and IHSS scores improved (decreased) from 31.6 (8.3) to 15.3 (8.5). Improvements were also observed during OLT in each individual IHSS item and in FOSQ-10 and WPAI:SHP scores. Thirty-five (22.7%) participants discontinued during OLT and SDP, 22 (14.3%) due to treatment-emergent adverse events (TEAEs) during OLT and SDP. The most frequent TEAEs in the first 4 weeks were nausea, headache, dizziness, and dry mouth; TEAE incidence decreased throughout OLT and SDP (weeks 1-4, n = 87 [56.5%]; weeks 13-16, n = 39 [31.7%]).

CONCLUSION

During open-label treatment with LXB, participants showed clinically meaningful improvements in idiopathic hypersomnia symptoms and in quality of life and functional measures. TEAE incidence declined over LXB titration and optimization.

Development of a lower-sodium oxybate formulation for the treatment of patients with narcolepsy and idiopathic hypersomnia

INTRODUCTION

Sodium oxybate (SXB) is a standard of care for cataplexy, excessive daytime sleepiness, and disrupted nighttime sleep in narcolepsy. At recommended dosages in adults (6-9 g/night), SXB increases daily dietary intake of sodium by 1100-1640 mg. Because excess sodium intake is associated with increased blood pressure and cardiovascular risk, an oxybate formulation containing 92% less sodium than SXB (lower-sodium oxybate; LXB) was developed to provide an alternative oxybate treatment option. In 2020, LXB was approved for treatment of cataplexy or excessive daytime sleepiness in patients 7 years of age and older with narcolepsy, and in 2021, for treatment of idiopathic hypersomnia in adults.

AREAS COVERED

Development of LXB from initial concept to regulatory approval is described, including formulation development and preclinical and clinical studies. Pharmacokinetic parameters and bioequivalence evaluations from phase 1 clinical trials are detailed. Efficacy and safety results from phase 3 clinical trials of LXB in patients with narcolepsy or idiopathic hypersomnia are presented and discussed.

EXPERT OPINION

Reducing sodium from high sodium‒containing medications is an important step to offset cardiovascular risks associated with high sodium consumption. The development of LXB exemplifies the importance of a collaborative approach to drug development, with patient needs paramount.

PLAIN LANGUAGE SUMMARY

Sodium oxybate (Xyrem®) is a medication for people with narcolepsy aged 7 years and older. Xyrem treats symptoms of excessive daytime sleepiness (EDS) or cataplexy (attacks of muscle weakness caused by emotion) in narcolepsy. At the recommended dosages in adults, Xyrem adds a large amount of sodium to daily dietary intake. Too much sodium in the diet is associated with increased blood pressure and risks of damage to the heart and blood vessels. Researchers used calcium, magnesium, and potassium ions in addition to a small amount of sodium to make a new oxybate medication, called Xywav®, that has 92% less sodium than Xyrem. Xywav and Xyrem were similar in laboratory and animal studies. In people, the body absorbs and processes Xywav slightly differently than Xyrem, but Xywav treatment has been shown to work the same to reduce symptoms of cataplexy and EDS in people with narcolepsy and is approved by the US Food and Drug Administration. Another neurological disorder with EDS is called idiopathic hypersomnia. Based on a clinical study, Xywav also reduced EDS and other symptoms in people with idiopathic hypersomnia. Side effects with Xywav are similar to those seen in previous studies with Xyrem.

Sleep inertia measurement with the psychomotor vigilance task in idiopathic hypersomnia

STUDY OBJECTIVES

Sleep inertia is a frequent and disabling symptom in idiopathic hypersomnia (IH), but poorly defined and without objective measures. The study objective was to determine whether the psychomotor vigilance task (PVT) can reliably measure sleep inertia in patients with IH or other sleep disorders (non-IH).

METHODS

Sixty-two (51 women, mean age: 27.7±9.2) patients with IH and 140 (71 women, age: 33.3±12.1) with non-IH (narcolepsy=29, non-specified hypersomnolence NSH=47, obstructive sleep apnea=39, insomnia=25) were included. Sleep inertia and sleep drunkenness in the last month (M-sleep inertia) and on PVT day (D-sleep inertia) were assessed with three items of the Idiopathic Hypersomnia Severity Scale (IHSS), in drug-free conditions. The PVT was performed four times (7:00 PM, and 7:00, 7:30 and 11:00 AM) and three metrics were used: lapses, mean 1/Reaction Time (RT), slowest 10% 1/RT.

RESULTS

Sleep inertia was more frequent in patients with IH than non-IH (56.5% and 43.6% with severe sleep inertia in the past month, including 24% and 12% with sleep drunkenness). Lapse number increase and slowest 10% 1/RT decrease, particularly at 7:00 and 7:30AM, were proportional with M-sleep inertia severity, but regardless of sleep drunkenness and sleep disorders. Similar results were obtained when PVT results were compared in patients with/without D-sleep inertia, with the largest increase of the lapse number at 7:00 and 7:30AM associated with severe sleep inertia and sleep drunkenness.

CONCLUSION

PVT is a reliable and objective measure of sleep inertia that might be useful for its characterization, management and follow-up in patients with IH.

Observation and Interview-based Diurnal Sleepiness Inventory for measurement of sleepiness in patients referred for narcolepsy or idiopathic hypersomnia

STUDY OBJECTIVES

First, to determine whether the 3-item Observation and Interview-based Diurnal Sleepiness Inventory (ODSI) measures the degree of excessive daytime sleepiness in patients with suspected narcolepsy or idiopathic hypersomnia (IH). Second, to assess the correlation between the ODSI and the Epworth Sleepiness Scale (ESS) as well as objective polysomnographic measurements. Third, to test the accuracy of the ODSI to detect narcolepsy or IH (narcolepsy/IH) compared with the ESS.

METHODS

A total of 181 patients complaining of excessive daytime sleepiness filled in the ESS and the ODSI and underwent measurements including actigraphy, full-night polysomnography, Multiple Sleep Latency Test, and 24-hour bedrest sleep recording.

RESULTS

Narcolepsy or IH was diagnosed in 76 patients. The ODSI found excessive daytime sleepiness in 92.3% of all patients and in 98.7% of those diagnosed with narcolepsy/IH. In the whole population, the ODSI was significantly positively correlated with the ESS (R = .547; 95% confidence interval: .436, .642; P < .001) and weakly with 24-hour total sleep time on bedrest recording (R = .208; 95% confidence interval: .056, .350; P = .047) but not with the Multiple Sleep Latency Test. The ODSI offered a higher negative (92.9%) and positive (44.9%) predictive value to detect narcolepsy/IH than did the ESS (66.7% and 43.3%, respectively). In the IH group, the ODSI's third-item score (daily sleepiness duration) was significantly higher in patients with than without increased 24-hour total sleep time (P = .023).

CONCLUSIONS

The ODSI is a brief, simple first-line questionnaire that explores both intensity and duration of daytime sleepiness and offers a high sensitivity to detect narcolepsy and IH.

Cognitive dysfunction in central disorders of hypersomnolence: A systematic review

Central disorders of hypersomnolence (CDH) are characterized by excessive daytime sleepiness not related to comorbid sleep or medical disturbances. We systematically examined scientific literature on cognitive functions in patients suffering from CDH. Forty-eight studies proved eligible and were analyzed separately for Narcolepsy Type 1 (NT1), Narcolepsy Type 2 (NT2), Idiopathic hypersomnia (IH) and Kleine-Levin syndrome (KLS). Results were grouped into the cognitive domains of attention, memory, executive functions and higher order cognition. Consistent attention impairments emerged in NT1, NT2 and IH patients, with NT1 patients showing the most compromised profile. Memory functions are largely unimpaired in CDH patients except for KLS patients who display memory deficit. Executive functions and higher-order cognition have been assessed in NT1 while they received little-to-no attention in the other CDH. NT1 patients display high performance in executive functions but exhibit a complex pattern of impairment in higher-order cognition, showing poor decision-making and impaired emotional processing. Moreover, NT1 patients show increased creative abilities. Assessing and monitoring cognitive impairments experienced by CDH patients will allow the design of personalized interventions, parallel to pharmacological treatment, aimed at improving daytime functioning and quality of life of these patients.

Regional neurodegeneration correlates with sleep-wake dysfunction after stroke

Sleep-wake disruption is a key modifiable risk factor and sequela of stroke. The pathogenesis of poststroke sleep dysfunction is unclear. It is not known whether poststroke sleep pathology is due to focal infarction to sleep-wake hubs or to accelerated poststroke neurodegeneration in subcortical structures after stroke. We characterize the first prospective poststroke regional brain volumetric and whole-brain, fiber-specific, white matter markers of objectively measured sleep-wake dysfunction. We hypothesized that excessively long sleep (>8 h) duration and poor sleep efficiency (<80%) measured using the SenseWear Armband 3-months poststroke (n = 112) would be associated with reduced regional brain volumes of a priori-selected sleep-wake regions of interest when compared to healthy controls with optimal sleep characteristics (n = 35). We utilized a novel technique known as a whole-brain fixel-based analysis to investigate the fiber-specific white matter differences in participants with long sleep duration. Stroke participants with long sleep (n = 24) duration exhibited reduced regional volumes of the ipsilesional thalamus and contralesional amygdala when compared with controls. Poor sleep efficiency after stroke (n = 29) was associated with reduced ipsilesional thalamus, contralesional hippocampus, and contralesional amygdala volumes. Whole-brain fixel-based analyses revealed widespread macrostructural degeneration to the corticopontocerebellar tract in stroke participants with long sleep duration, with fiber reductions of up to 40%. Neurodegeneration to subcortical structures, which appear to be vulnerable to accelerated brain volume loss after stroke, may drive sleep-wake deficiencies poststroke, independent of lesion characteristics and confounding comorbidities. We discuss these findings in the context of the clinicopathological implications of sleep-related neurodegeneration and attempt to corroborate previous mechanistic-neuroanatomical findings.

Narcolepsy type 1: what have we learned from genetics?

Type-1 narcolepsy is a severe neurological disorder with distinct characteristic of loss of hypocretin neurotransmitter. Genetic analysis in type-1 narcolepsy have revealed a unique signal pointing toward autoimmune, rather than psychiatric origin. While type-1 narcolepsy has been intensively studied, the other subtypes of hypersomnolence, narcolepsy, and hypersomnia are less thoroughly understood. This review summarizes the latest breakthroughs in the field in narcolepsy. The goal of this article is to help the reader to understand better the risk from genetic factors and their interplay with immune, genetic, and epidemiological aspects in narcolepsy.

Multiple Sleep Latency Test: when are 4 naps enough?

STUDY OBJECTIVES

The Multiple Sleep Latency Test (MSLT) is central to the diagnosis of narcolepsy and idiopathic hypersomnia. This study is the first to assess the impact of a 5-nap protocol on meeting MSLT-derived diagnostic criteria in a general cohort referred for MSLT, without selection bias.

METHODS

Data for all MSLTs performed at 2 tertiary sleep units in Australia between May 2012 and May 2018 were retrospectively assessed for the impact of the fifth nap on mean sleep latency (MSL) and sleep onset rapid eye movement periods.

RESULTS

There were 122 MSLTs included. The MSL was 8.7 ± 5.1 minutes after 4 naps, compared with 9.2 ± 5.2 minutes for 5 naps (P < .0001). In 8 cases, inclusion of the fifth nap changed the MSL to a value above the diagnostic threshold of 8 minutes. There were no instances in which the MSL moved to ≤ 8 minutes based on fifth nap data. A sleep onset rapid eye movement period occurred in the fifth nap in 9 patients and altered the interpretation in 2 cases.

CONCLUSIONS

The fifth nap in an MSLT is associated with an increased MSL, although this difference is rarely clinically significant. In patients with borderline MSL or 1 sleep onset rapid eye movement period after 4 naps, a fifth nap can alter the outcome and should be performed. However, for many cases, a 4-nap MSLT protocol will suffice, potentially allowing resource savings without compromising diagnostic accuracy. We propose the adoption of a conditional 4-nap or 5-nap protocol based on specific criteria.

Idiopathic hypersomnia: a homogeneous or heterogeneous disease?

INTRODUCTION

Idiopathic hypersomnia (IH) is a rare orphan disease characterized by excessive daytime sleepiness, frequently accompanied by prolonged nocturnal sleep and difficulties awakening, termed sleep inertia or sleep drunkenness. Severe sleepiness usually causes a greater handicap than manifestations of narcolepsy.

METHODS

Forty-three IH patients (17 male, mean age 42.8 ± SD 12.2 years, range 20-67), diagnosed in the past 20 years according to ICSD-2 or ICSD-3 criteria were invited for clinical examination to evaluate the course, manifestations and severity of the disease, as well as clinical comorbidities. The patients completed a set of questionnaires scoring sleepiness, sleep inertia, fatigue, depression, anxiety, circadian preference, and quality of life.

RESULTS

IH patients were divided according to the duration of nocturnal sleep at the time of their diagnosis into two cohorts: (1) with normal sleep duration (n = 25, 58.1%) and (2) with long sleep duration (n = 18, 41.9%). The mean duration of ad libitum sleep per 22 h in the second cohort was 732.0 ± 115.4 min (range 603-1100), and women markedly prevailed (n = 14, 77.8%). Age at disease onset was younger in the group with long sleep duration (21.2 ± 11.4 years versus 28.1 ± 13.6 years, p = 0.028), their MSLT latency was longer (7.2 ± 3.7 min versus 5.1 ± 1.7 min, p = 0.005), a history of sleep inertia prevailed (p = 0.005), and daily naps were mostly non-refreshing (p = 0.014). Additionally, questionnaires in the group with long sleep duration showed more severe sleep inertia (p = 0.007), fatigue (p = 0.004), and a tendency towards evening chronotype (p = 0.001).

CONCLUSIONS

IH patients with long sleep duration differ clinically as well as by objective measures at the time of diagnosis and in long-term follow up from IH patients without long 24-h sleep time. In our opinion they represent an independent clinical entity to be considered in the revised ICSD-3 criteria.

Efficacy and safety of modafinil in patients with idiopathic hypersomnia without long sleep time: a multicenter, randomized, double-blind, placebo-controlled, parallel-group comparison study

BACKGROUND

Few treatments are available for patients with idiopathic hypersomnia (IH). Modafinil, an established treatment for narcolepsy, was tested for efficacy and safety in Japanese patients with IH without long sleep time.

METHODS

This multicenter, randomized, double-blind, placebo-controlled, parallel-group comparison study was conducted at 20 institutions in Japan. Patients who met the diagnostic criteria of IH in the International Classification of Sleep Disorders (second edition) were included. The study comprised a ≥17-day observation period and a 3-week treatment period during which modafinil (200 mg) or placebo was administered orally once daily (in the morning). The primary efficacy endpoint was change in mean sleep latency on the Maintenance of Wakefulness Test (MWT). Adverse events (AEs) were also recorded to evaluate safety.

RESULTS

In total, 123 patients were screened and 71 were randomized to receive modafinil (N = 34) or placebo (N = 37). Patients treated with modafinil experienced a significantly prolonged mean sleep latency on the MWT at the end of the study compared with placebo (5.02 min, 95% confidence interval: 3.26-6.77 min; p < 0.001). AEs occurred in 58.8% (20/34) and 27.0% (10/37) of patients in the modafinil and placebo groups, respectively. Frequent AEs in the modafinil group were headache (n = 6), dry mouth (n = 3), and nausea (n = 3); no clinically significant AEs occurred.

CONCLUSION

Modafinil was shown to be an effective and safe treatment for excessive daytime sleepiness in patients with IH without long sleep time.

CLINICAL TRIAL REGISTRATION

JapicCTI; 142539.

Pharmacologic Management of Excessive Daytime Sleepiness

Excessive daytime sleepiness (EDS) is related to medical and social problems, including mental disorders, physical diseases, poor quality of life, and so forth. According to the International Classification of Sleep Disorders, Third Edition, diseases that result from EDS are narcolepsy type 1, narcolepsy type 2, idiopathic hypersomnia, hypersomnia due to a medical disorder, and others. EDS is usually treated using amphetamine-like central nervous system stimulants or modafinil and its R-enantiomer, armodafinil, wake-promoting compounds unrelated to amphetamines; a variety of new drugs are under development. The side effects of some stimulants are potent and careful selection and management are required.

Establishing the objective sleep phenotype in hypersomnolence disorder with and without comorbid major depression

STUDY OBJECTIVES

To clarify whether hypersomnolence disorder is associated with a specific sleep phenotype and altered neurophysiological function in persons with and without hypersomnolence disorder and major depressive disorder (MDD).

METHODS

Eighty-three unmedicated persons with and without hypersomnolence disorder and/or MDD underwent ad libitum high-density EEG polysomnography. Clinical and sleep architecture variables were compared between groups. Topographic patterns of slow-wave activity (SWA) relative to healthy controls were compared, with correlations between topographic SWA and daytime sleepiness assessed. Reductions in SWA in hypersomnolence disorder were mapped to specific cortical areas using source localization.

RESULTS

Regardless of the presence or absence of comorbid MDD, persons with hypersomnolence disorder had increased sleep duration relative to both controls and persons with MDD without hypersomnolence. Participants with hypersomnolence disorder also demonstrated reduced bilateral centroparietal low-frequency activity during nonrapid eye movement sleep relative to controls, a pattern not observed in persons with MDD but without hypersomnolence. SWA in these regions was negatively correlated with subjective measures of daytime sleepiness. Source localization demonstrated reductions in SWA in the supramarginal gyrus, somatosensory, and transverse temporal cortex in participants with hypersomnolence disorder.

CONCLUSIONS

Hypersomnolence disorder is characterized by increased sleep duration with normal sleep continuity, regardless of the presence or absence of comorbid depression. Reduced local SWA may be a specific neurophysiological finding in hypersomnolence disorder. Further research is warranted to elucidate the mechanisms through which these cortical changes are related to clinical complaints of daytime sleepiness.

Neuroimaging of Narcolepsy and Primary Hypersomnias

Advances in neuroimaging open up the possibility for new powerful tools to be developed that potentially can be applied to clinical populations to improve the diagnosis of neurological disorders, including sleep disorders. At present, the diagnosis of narcolepsy and primary hypersomnias is largely limited to subjective assessments and objective measurements of behavior and sleep physiology. In this review, we focus on recent neuroimaging findings that provide insight into the neural basis of narcolepsy and the primary hypersomnias Kleine-Levin syndrome and idiopathic hypersomnia. We describe the role of neuroimaging in confirming previous genetic, neurochemical, and neurophysiological findings and highlight studies that permit a greater understanding of the symptoms of these sleep disorders. We conclude by considering some of the remaining challenges to overcome, the existing knowledge gaps, and the potential role for neuroimaging in understanding the pathogenesis and clinical features of narcolepsy and primary hypersomnias.

Association of Inattention, Hyperactivity, and Hypersomnolence in Two Clinic-Based Adult Cohorts

Objective: To assess the relationship between excessive daytime sleepiness (EDS), inattention, and hyperactivity/impulsivity in adults with ADHD and central hypersomnia. Method: Drug-free adult patients with ADHD (n = 100) or hypersomnia (n = 100) were evaluated using a structured clinical interview and self-report questionnaires on ADHD symptoms and EDS. Results: In all, 61% of patients with hypersomnia had clinically significant ADHD symptoms with 25% having an ADHD diagnosis (with both childhood and adulthood ADHD symptoms) and 36% ADHD-like symptoms, without history of childhood ADHD. EDS was reported in 47% of patients with ADHD, among whom 22% had a hypersomnolence disorder. Conclusion: We confirmed the high frequency of ADHD and ADHD-like symptoms in central hypersomnia, and of EDS and hypersomnolence in ADHD in adults. The nature of the link between EDS, inattention, and hyperactivity appears to be complex that may involve either a cause-effect relationship or intrinsic features of a similar neurodevelopmental dysfunction.

A Guide to Management of Sleepiness in ESKD

Daytime sleepiness, also known as hypersomnolence, is common among patients receiving maintenance dialysis and following successful kidney transplantation. Sleepiness may be secondary to medical comorbid conditions, medication side effect, insufficient sleep syndrome, and sleep-disordered breathing or the result of a primary central disorder of hypersomnolence, such as narcolepsy. Unrecognized and untreated sleep disorders are associated with substantial morbidity and mortality among patients with end-stage kidney disease. Effective management of hypersomnolence can improve quality of life in patients with kidney disease. This review focuses on the principal causes of sleepiness in patients with end-stage kidney disease. Awareness of these disorders by treating nephrologists is crucial. This review provides a systematic approach to guide providers through the recognition, early diagnosis, and treatment of hypersomnolence, which is commonly encountered in this patient population. Areas of future research are also suggested.

Topical Review: A Biopsychosocial Framework for Pediatric Narcolepsy and Idiopathic Hypersomnia

OBJECTIVE

Provide an overview of current research findings in pediatric central disorders of hypersomnolence (CDH) and propose a biopsychosocial model for clinical management, with a focus on interdisciplinary care and future directions for research and clinical practice.

METHODS

Literature review drawing from pediatric and adult narcolepsy, as well as pediatric sleep and chronic pain research to develop an integrative biopsychosocial model for pediatric CDH.

RESULTS

Youth with CDH are vulnerable to impairments in academics, emotional, and behavioral functioning, activity engagement and quality of life (QOL). There is a complex interrelationship between neurobiological features of disease, treatment-related factors, and psychological, sleep-related, and contextual factors across development. Research is limited largely to adults and pediatric narcolepsy type 1 and the mechanisms and evolution of morbidity remain poorly understood.

CONCLUSIONS

In addition to first-line treatment (pharmacotherapy), routine screening of bio-behavioral and psychosocial functioning and QOL is needed to identify risk for compromised functioning warranting adjunctive interventions with behavioral health specialists.

Prevalence of attention deficit hyperactivity disorder symptoms in narcolepsy: a systematic review

OBJECTIVE

Narcolepsy is characterized by excessive daytime sleepiness and cataplexy. Attention deficit hyperactivity disorder (ADHD) is characterized by hyperactivity, inattention, and impulsivity. However, despite their differences, both narcolepsy and ADHD share the symptoms of sleep disturbance and excessive daytime sleepiness. Recent studies have suggested a link between the two disorders. The objective of systematic review was to assess the prevalence of ADHD symptoms in narcolepsy.

METHODS

We performed a systematic search of MEDLINE (inception to December 2018) and EMBASE (inception to December 2018) for English publications of human studies using the keywords "narcolepsy" and "ADHD".

RESULTS

Five studies examining a total of 328 patients met the eligibility criteria for this study examining the prevalence of ADHD symptoms in narcolepsy. The pooled prevalence of ADHD symptoms in narcolepsy was 33.0%. Two studies using the international classification of sleep disorders, second edition (ICSD-2) observed a pooled prevalence of ADHD symptoms in narcolepsy of 25.0%, while two other studies that relied on the ICSD-3 criteria observed a pooled prevalence of ADHD symptoms in narcolepsy of 36.4%.

CONCLUSIONS

The prevalence of ADHD symptoms was >30%, making it an important comorbidity of narcolepsy. Future studies should be performed to better assess the relationship between ADHD and narcolepsy.

Update on the Treatment of Idiopathic Hypersomnia

Purpose of Review

Idiopathic hypersomnia is an incapacitating disorder with a profound impact on daytime performance and quality of life. The most commonly used treatment modalities are lifestyle advice and pharmacological therapy. We present an update on the evidence concerning treatment options for idiopathic hypersomnia.

Recent Findings

Evidence for non-pharmacological interventions is lacking; improvement in symptoms on introducing these interventions is often less pronounced than in narcolepsy. Additional pharmacological treatment is therefore usually initiated. The few treatment studies that have been performed are hampered by small sample sizes and the use of variable and often insufficiently validated outcome parameters for the whole spectrum of idiopathic hypersomnia symptoms.

Conclusion

Evidence on treatment is scarce. Since the efficacy of modafinil is consistently described and there is much experience with this substance, it is reasonable to start with modafinil as a first choice treatment. Methylphenidate and dexamphetamine are good alternatives. In the future, newer drugs such as sodium oxybate, pitolisant, and solriamfetol might be authorized for use in idiopathic hypersomnia.

Is Idiopathic Hypersomnia a Circadian Rhythm Disorder?

Purpose of review

The pathophysiology of idiopathic hypersomnia remains unclear, but some of its clinical features suggest the possibility of circadian dysfunction. This review will provide an overview of recent studies of circadian biology that have begun to elucidate the potential role of circadian rhythm dysfunction in idiopathic hypersomnia.

Recent findings

Clinically, people with idiopathic hypersomnia tend to have both a late chronotype and prominent sleep inertia or sleep drunkenness. Melatonin and cortisol profiles in people with IH confirm this tendency toward phase delay. More recently, it has been suggested that the night phase as defined by melatonin profile or period length as defined by BMA1 in dermal fibroblasts may also be prolonged in people with IH. Additionally, amplitude of melatonin rhythm and circadian gene expression, particularly BMAL1, PER1, and PER2, may be impaired in this disease.

Summary

Clinical features, melatonin profiles, and circadian gene expression all suggest abnormalities of the circadian system may be a contributor to the pathogenesis of IH.

Sleep-Related Disorders in Neurology and Psychiatry

BACKGROUND

Sleep-related disorders are a group of illnesses with marked effects on patients' quality of life and functional ability. Their diagnosis and treatment is a matter of common interest to multiple medical disciplines.

METHODS

This review is based on relevant publications retrieved by a selective search in PubMed (Medline) and on the guide- lines of the German Society for Sleep Medicine, the German Neurological Society, and the German Association for Psychiatry, Psychotherapy and Psychosomatics.

RESULTS

A pragmatic classification of sleep disorders by their three chief complaints-insomnia, daytime somnolence, and sleep-associated motor phenomena-enables tentative diagnoses that are often highly accurate. Some of these disorders can be treated by primary care physicians, while others call for referral to a neurologist or psychiatrist with special experience in sleep medicine. For patients suffering from insomnia as a primary sleep disorder, rather than a symptom of another disease, meta-analyses have shown the efficacy of cognitive behavioral therapy, with high average effect sizes. These patients, like those suffering from secondary sleep disorders, can also benefit from drug treatment for a limited time. Studies have shown marked improvement of sleep latency and sleep duration from short-term treatment with benzodiazepines and Z-drugs (non- benzodiazepine agonists such as zolpidem and zopiclone), but not without a risk of tolerance and dependence. For sleep disorders with the other two main manifestations, specific drug therapy has been found to be beneficial.

CONCLUSION

Sleep disorders in neurology and psychiatry are a heterogeneous group of disorders with diverse manifestations. Their proper diagnosis and treatment can help prevent secondary diseases and the worsening of concomitant conditions. Care structures for the treatment of sleep disorders should be further developed.

Clinical neurophysiology of CNS hypersomnias

Central nervous system hypersomnias (narcolepsy type 1 and type 2, idiopathic hypersomnia, and Kleine-Levin syndrome) are orphan sleep disorders in which the predominant symptom is excessive daytime sleepiness. The evaluation of sleepiness requires rigorous clinical and neurophysiologic approaches that may include the Epworth Sleepiness Scale, multiple sleep latency tests, and the maintenance of wakefulness test. However, to date, no gold standard measurement of excessive sleepiness exists, and there are no quantifiable biologic markers. The main pathophysiologic feature of central hypersomnias is thought to reflect a deficiency of arousal systems, rather than an overactivity of sleep systems or an imbalance between those systems. Impaired neurotransmission of hypocretin/orexin (neuropeptides of the lateral hypothalamus) is involved in the neurobiology of narcolepsy with cataplexy (NT1). NT1 is a well-characterized disorder, due to the destruction of hypocretin/orexin neurons by a probable autoimmune process. The biologic hallmarks of the other central hypersomnias remain unknown, and neurophysiologic biomarkers are still of major importance for the diagnosis and characterization of those disorders.