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.

Narcolepsy Severity Scale-2 and Idiopathic Hypersomnia Severity Scale to better quantify symptoms severity and consequences in Narcolepsy type 2

STUDY OBJECTIVES

Narcolepsy type 2 (NT2) is an understudied central disorder of hypersomnolence sharing some similarities with narcolepsy type 1 and idiopathic hypersomnia (IH). We aimed: (1) to assess systematically the symptoms in patients with NT2, with self-reported questionnaires: Epworth Sleepiness Scale (ESS), Narcolepsy Severity Scale (NSS), IH Severity Scale (IHSS), and (2) to evaluate the responsiveness of these scales to treatment.

METHODS

One hundred and nine patients with NT2 (31.4 ± 12.2 years old, 47 untreated) diagnosed according to ICSD-3 were selected in a Reference Center for Narcolepsy. They all completed the ESS, subgroups completed the modified NSS (NSS-2, without cataplexy items) (n = 95) and IHSS (n = 76). Some patients completed the scales twice (before/during treatment): 42 ESS, 26 NSS-2, and 30 IHSS.

RESULTS

Based on NSS-2, all untreated patients had sleepiness, 58% disrupted nocturnal sleep, 40% hallucinations, and 28% sleep paralysis. On IHSS, 76% reported a prolonged nocturnal sleep, and 83% sleep inertia. In the independent sample, ESS and NSS-2 scores were lower in treated patients, with same trend for IHSS scores. After treatment, ESS, NSS-2, and IHSS total scores were lower, with a mean difference of 3.7 ± 4.1, 5.3 ± 6.7, and 4.1 ± 6.2, respectively. The minimum clinically important difference between untreated and treated patients were 2.1 for ESS, 3.3 for NSS-2, and 3.1 for IHSS. After treatment, 61.9% of patients decreased their ESS > 2 points, 61.5% their NSS-2 > 3 points, and 53.3% their IHSS > 3 points.

CONCLUSIONS

NSS-2 and IHSS correctly quantified symptoms' severity and consequences in NT2, with good performances to objectify response to medications. These tools are useful for monitoring and optimizing NT2 management, and for use in clinical trials.

Idiopathic hypersomnia years after the diagnosis

Little attention has been paid to the long-term development of idiopathic hypersomnia symptoms and idiopathic hypersomnia comorbidities. The aim of this study was to describe the general health of patients with idiopathic hypersomnia years after the initial diagnosis, focusing on current subjective hypersomnolence and the presence of its other possible causes. Adult patients diagnosed with idiopathic hypersomnia ≥ 3 years ago at sleep centres in Prague and Kosice were invited to participate in this study. A total of 60 patients were examined (age 47.3 ± SD = 13.2 years, 66.7% women). In all participants, their hypersomnolence could not be explained by any other cause but idiopathic hypersomnia at the time of diagnosis. The mean duration of follow-up was 9.8 + 8.0 years. Fifty patients (83%) reported persisting hypersomnolence, but only 33 (55%) had no other disease that could also explain the patient's excessive daytime sleepiness and/or prolonged sleep. In two patients (3%), the diagnosis in the meantime had changed to narcolepsy type 2, and 15 patients (25%) had developed a disease or diseases potentially causing hypersomnolence since the initial diagnosis. Complete hypersomnolence resolution without stimulant treatment lasting longer than 6 months was reported by 10 patients (17%). To conclude, in a longer interval from the diagnosis of idiopathic hypersomnia, hypersomnolence may disappear or may theoretically be explained by another newly developed disease, or the diagnosis may be changed to narcolepsy type 2. Thus, after 9.8 years, only 55% of the examined patients with idiopathic hypersomnia had a typical clinical picture of idiopathic hypersomnia without doubts about the cause of the current hypersomnolence.

Objective evaluation of excessive daytime sleepiness

Excessive daytime sleepiness (EDS) is multifactorial. It combines, among other things, an excessive propensity to fall asleep ("physiological sleepiness") and a continuous non-imperative sleepiness (or drowsiness/hypo-arousal) leading to difficulties remaining awake and maintaining sustained attention and vigilance over the long term ("manifest sleepiness"). There is no stand-alone biological measure of EDS. EDS measures can either capture the severity of physiological sleepiness, which corresponds to the propensity to fall asleep, or the severity of manifest sleepiness, which corresponds to behavioral consequences of sleepiness and reduced vigilance. Neuropsychological tests (The psychomotor vigilance task (PVT), Oxford Sleep Resistance Test (OSLeR), Sustained Attention to Response Task (SART)) explore manifest sleepiness through several sustained attention tests but the lack of normative values and standardized protocols make the results difficult to interpret and use in clinical practice. Neurophysiological tests explore the two main aspects of EDS, i.e. the propensity to fall asleep (Multiple sleep latency test, MSLT) and the capacity to remain awake (Maintenance of wakefulness test, MWT). The MSLT and the MWT are widely used in clinical practice. The MSLT is recognized as the "gold standard" test for measuring the severity of the propensity to fall asleep and it is a diagnostic criterion for narcolepsy. The MWT measures the ability to stay awake. The MWT is not a diagnostic test as it is recommended only to evaluate the evolution of EDS and efficacy of EDS treatment. Even if some efforts to standardize the protocols for administration of these tests have been ongoing, MSLT and MWT have numerous limitations: age effect, floor or ceiling effects, binding protocol, no normal or cutoff value (or determined in small samples), and no or low test-retest values in some pathologies. Moreover, the recommended electrophysiological set-up and the determination of sleep onset using the 30‑sec epochs scoring rule show some limitations. New, more precise neurophysiological techniques should aim to detect very brief periods of physiological sleepiness and, in the future, the brain local phenomenon of sleepiness likely to underpin drowsiness, which could be called "physiological drowsiness".

Is there a role for repeating the multiple sleep latency test across childhood when initially non-diagnostic?

BACKGROUND

The gold standard investigation for central disorders of hypersomnolence is the Multiple Sleep Latency Test (MSLT). As the clinical features of these disorders of hypersomnolence evolve with time in children, clinicians may consider repeating a previously non-diagnostic MSLT. Currently there are no guidelines available regards the utility and timing of repeating paediatric MSLTs.

METHODS

Retrospective review of children aged 3-18years with ≥2MSLTs between 2005 and 2022. Narcolepsy was defined as mean sleep latency (MSL) <8min with ≥2 sleep onset REM (SOREM); idiopathic hypersomnia (IH) was defined as MSL <8min with <2 SOREM. MSLTs not meeting these criteria were labelled non-diagnostic.

RESULTS

19 children (9 female) with initial non-diagnostic MSLT underwent repeat MSLT, with 6 proceeding to a 3rd MSLT following 2 non-diagnostic MSLTs. The 2nd MSLT resulted in diagnosis in 6/19 (32 %) (3 narcolepsy, 3 IH); and 2/6 (33 %) 3rd MSLT were diagnostic (2 IH). Median age at initial MSLT was 7.5y (range 3.4-17.8y), with repeat performed after median of 2.9y (range 0.9-8.2y), and 3rd after a further 1.9 years (range 1.2-4.2y). Mean change in MSL on repeat testing was -2min (range -15.5min to +4.9min, p = 0.18). Of the 8 diagnostic repeat MSLTs, in addition to the MSL falling below 8 min, 2 children also developed ≥2 SOREM that had not been previously present.

CONCLUSIONS

A third of repeat MSLTs became diagnostic, suggesting repeat MSLT should be considered in childhood if clinical suspicion persists. Further work needs to address the ideal interval between MSLTs and diagnostic cut-points specific to the paediatric population.

Sleepy Kids: are the current diagnostic criteria for multiple sleep latency tests enough?

Excessive daytime sleepiness (EDS) is common in childhood and is currently quantified using adult criteria on a multiple sleep latency test (MSLT). This study aimed to describe paediatric MSLT results, particularly focussing on a previously proposed alternative mean sleep latency (MSL) threshold for children of 12 min, and assess the impact of a 5th nap. We performed a retrospective analysis of MSLTs at a single paediatric centre from 2004 to 2021. Narcolepsy was defined as a mean sleep latency (MSL) ≤8min with ≥2 sleep onset REM (SOREM) periods. Idiopathic Hypersomnia (IH) was defined as a MSL ≤8min with <2 SOREMs. An ambiguous MSLT result was defined as a MSL 8-12min and/or ≥2 SOREM periods. Of 214 MSLTs [50 % female, median age 14.0y (range 3.3-20.1y)], narcolepsy was diagnosed in 48 (22 %), IH in 22 (10 %) and the result was ambiguous in 44 (21 %). Those with ambiguous MSLT results were older (15.6 vs 13.4y, p = 0.006) with a higher proportion of females (61 % vs 35 %, p = 0.01) in comparison to the narcolepsy group. A 5th nap was performed in 60 (28 %) of MSLTs and only changed the outcome in one case. In conclusion, MSLT results are borderline in 21 % of paediatric cases, suggesting that current adult diagnostic criteria may miss narcolepsy and IH in children. A 5th nap usually makes no difference or increases the MSL, suggesting that a four nap MSLT protocol could be used apart from rare cases where the result is borderline after the 4th nap.

Disentangling the complex landscape of sleep-wake disorders with data-driven phenotyping: A study of the Bernese center

BACKGROUND AND PURPOSE

The diagnosis of sleep-wake disorders (SWDs) is challenging because of the existence of only few accurate biomarkers and the frequent coexistence of multiple SWDs and/or other comorbidities. The aim of this study was to assess in a large cohort of well-characterized SWD patients the potential of a data-driven approach for the identification of SWDs.

METHODS

We included 6958 patients from the Bernese Sleep Registry and 300 variables/biomarkers including questionnaires, results of polysomnography/vigilance tests, and final clinical diagnoses. A pipeline, based on machine learning, was created to extract and cluster the clinical data. Our analysis was performed on three cohorts: patients with central disorders of hypersomnolence (CDHs), a full cohort of patients with SWDs, and a clean cohort without coexisting SWDs.

RESULTS

A first analysis focused on the cohort of patients with CDHs and revealed four patient clusters: two clusters for narcolepsy type 1 (NT1) but not for narcolepsy type 2 or idiopathic hypersomnia. In the full cohort of SWDs, nine clusters were found: four contained patients with obstructive and central sleep apnea syndrome, one with NT1, and four with intermixed SWDs. In the cohort of patients without coexisting SWDs, an additional cluster of patients with chronic insomnia disorder was identified.

CONCLUSIONS

This study confirms the existence of clear clusters of NT1 in CDHs, but mainly intermixed groups in the full spectrum of SWDs, with the exception of sleep apnea syndromes and NT1. New biomarkers are needed for better phenotyping and diagnosis of SWDs.

Efficacy of once-nightly sodium oxybate (FT218) in narcolepsy type 1 and type 2: post hoc analysis from the Phase 3 REST-ON Trial

STUDY OBJECTIVES

Post hoc analyses from the phase 3 REST-ON trial evaluated efficacy of extended-release once-nightly sodium oxybate (ON-SXB; FT218) vs placebo for daytime sleepiness and disrupted nighttime sleep in narcolepsy type 1 (NT1) and 2 (NT2).

METHODS

Participants were stratified by narcolepsy type and randomized 1:1 to ON-SXB (4.5 g, week 1; 6 g, weeks 2-3; 7.5 g, weeks 4-8; and 9 g, weeks 9-13) or placebo. Assessments included mean sleep latency on Maintenance of Wakefulness Test (MWT) and Clinical Global Impression-Improvement (CGI-I) rating (coprimary endpoints) and sleep stage shifts, nocturnal arousals, and patient-reported sleep quality, refreshing nature of sleep, and Epworth Sleepiness Scale (ESS) score (secondary endpoints) separately in NT1 and NT2 subgroups.

RESULTS

The modified intent-to-treat population comprised 190 participants (NT1, n = 145; NT2, n = 45). Significant improvements were demonstrated with ON-SXB vs placebo in sleep latency for NT1 (all doses, p < .001) and NT2 (6 and 9 g, p < .05) subgroups. Greater proportions of participants in both subgroups had CGI-I ratings of much/very much improved with ON-SXB vs placebo. Sleep stage shifts and sleep quality significantly improved in both subgroups (all doses vs placebo, p < .001). Significant improvements with all ON-SXB doses vs placebo in refreshing nature of sleep (p < .001), nocturnal arousals (p < .05), and ESS scores (p ≤ .001) were reported for NT1 with directional improvements for NT2.

CONCLUSIONS

Clinically meaningful improvements of a single ON-SXB bedtime dose were shown for daytime sleepiness and DNS in NT1 and NT2, with less power for the limited NT2 subgroup.

Evaluation of hypersomnolence: From symptoms to diagnosis, a multidimensional approach

Hypersomnolence is a major public health issue given its high frequency, its impact on academic/occupational functioning and on accidentology, as well as its heavy socio-economic burden. The positive and aetiological diagnosis is crucial, as it determines the therapeutic strategy. It must consider the following aspects: i) hypersomnolence is a complex concept referring to symptoms as varied as excessive daytime sleepiness, excessive need for sleep, sleep inertia, or drowsiness, all of which warrant specific dedicated investigations; ii) the boundary between physiological and abnormal hypersomnolence is blurred, since most symptoms can be encountered in the general population to varying degrees without being considered as pathological, meaning that their severity, frequency, context of occurrence and related impairment need to be carefully assessed; iii) investigation of hypersomnolence relies on scales/questionnaires as well as behavioural and neurophysiological tests, which measure one or more dimensions, keeping in mind the possible discrepancy between objective and subjective assessment; iv) aetiological reasoning is driven by knowledge of the main sleep regulation mechanisms, epidemiology, and associated symptoms. The need to assess hypersomnolence is growing, both for its management, and for assessing the efficacy of treatments. The landscape of tools available for investigating hypersomnolence is constantly evolving, in parallel with research into sleep physiology and technical advances. These investigations face the challenges of reconciling subjective perception and objective data, making tools accessible to as many people as possible and predicting the risk of accidents.

Repeated polysomnography and multiple sleep latency test in narcolepsy type 1 and other hypersomnolence disorders

BACKGROUND

The diagnosis of narcolepsy is based on clinical information, combined with polysomnography (PSG) and the Multiple Sleep Latency Test (MSLT). PSG and the MSLT are moderately reliable at diagnosing narcolepsy type 1 (NT1) but unreliable for diagnosing narcolepsy type 2 (NT2). This is a problem, especially given the increased risk of a false-positive MSLT in the context of circadian misalignment or sleep deprivation, both of which commonly occur in the general population.

AIM

We aimed to clarify the accuracy of PSG/MSLT testing in diagnosing NT1 versus controls without sleep disorders. Repeatability and reliability of PSG/MSLT testing and temporal changes in clinical findings of patients with NT1 versus patients with hypersomnolence with normal hypocretin-1 were compared.

METHOD

84 patients with NT1 and 100 patients with non-NT1-hypersomnolence disorders, all with congruent cerebrospinal fluid hypocretin-1 (CSF-hcrt-1) levels, were included. Twenty-five of the 84 NT1 patients and all the hypersomnolence disorder patients underwent a follow-up evaluation consisting of clinical assessment, PSG, and a modified MSLT. An additional 68 controls with no sleep disorders were assessed at baseline.

CONCLUSION

Confirming results from previous studies, we found that PSG and our modified MSLT accurately and reliably diagnosed hypocretin-deficient NT1 (accuracy = 0.88, reliability = 0.80). Patients with NT1 had stable clinical and electrophysiological presentations over time that suggested a stable phenotype. In contrast, the PSG/MSLT results of patients with hypersomnolence, and normal CSF-hcrt-1 had poor reliability (0.32) and low repeatability.

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.

Eyelid Closure Behavior of Patients with Idiopathic and Nonorganic Hypersomnia, Narcolepsy-Cataplexy, and Healthy Controls in the Maintenance of Wakefulness Test

Purpose

Differential diagnosis of central disorders of hypersomnolence remains challenging, particularly between idiopathic (IH) and nonorganic hypersomnia (NOH). We hypothesized that eyelid closure behavior in the maintenance of wakefulness test (MWT) could be a valuable biomarker.

Patients and Methods

MWT recordings of patients with IH, NOH, narcolepsy-cataplexy (NC), and healthy sleep-deprived controls (H) were retrospectively analyzed (15 individuals per group). For each MWT trial, visual scoring of face videography for partial (50-80%) and full eyelid closure (≥80%) was performed from "lights off" to the first microsleep episode (≥3 s).

Results

In all groups, the frequency and cumulative duration of periods with partial and full eyelid closure gradually increased toward the first microsleep episode. On the group level, significant differences occurred for the latency to the first microsleep episode (IH 21 min (18-33), NOH 23 min (17-35), NC 11 min (7-19), H 10 min (6-25); p = 0.009), the ratio between partial and full eyelid closure duration (IH 2.2 (0.9-3.1), NOH 0.5 (0-1.2), NC 2.8 (1.1-5), H 0.7 (0.4-3.3); p = 0.004), and the difference between full and partial eyelid closure duration in the five minutes prior to the first microsleep episode (∆full - partial eyelid closure duration: IH -16 s (-35 to 28); NOH 46 s (9-82); NC -6 s (-26 to 5); H 10 s (-4 to 18); p = 0.007). IH and NOH significantly differed comparing the ratio between partial and full eyelid closure (p = 0.005) and the difference between ∆full - partial eyelid closure duration in the five minutes prior to the first microsleep episode (p = 0.006).

Conclusion

In the MWT, eyelid closure behavior (∆full - partial) in the period prior to the first microsleep episode could be of value for discriminating NOH from other etiologies of excessive daytime sleepiness, particularly IH.

Central Disorders of Hypersomnolence

OBJECTIVE

The goals of this article are to describe the clinical approach to and management of patients with central disorders of hypersomnolence, and to understand and differentiate available diagnostic tools.

LATEST DEVELOPMENTS

Updated clinical practice guidelines for the treatment of central disorders of hypersomnolence and narcolepsy specifically highlight new treatment options. Approval for a lower-sodium oxybate formulation that contains 92% less sodium than the standard sodium oxybate for the treatment of narcolepsy and idiopathic hypersomnia adds to the number of medications available for these disorders, allowing for a more tailored management of symptoms.

ESSENTIAL POINTS

Central disorders of hypersomnolence are characterized by excessive daytime sleepiness that impacts daily functions. These disorders can be differentiated by obtaining a detailed clinical sleep history and by a thoughtful interpretation of sleep diagnostic testing. Tailoring treatment approaches to meet the needs of individuals and accounting for medical and psychiatric comorbidities may improve quality of life.

Narcolepsy and Idiopathic Hypersomnia

Narcolepsy types 1 and 2 and idiopathic hypersomnia are primary Central Nervous System (CNS) disorders of hypersomnolence characterized by profound daytime sleepiness and/or excessive sleep need. Onset of symptoms begins typically in childhood or adolescence, and children can have unique presentations compared with adults. Narcolepsy type 1 is likely caused by immune-mediated loss of orexin (hypocretin) neurons in the hypothalamus; however, the causes of narcolepsy type 2 and idiopathic hypersomnia are unknown. Existing treatments improve daytime sleepiness and cataplexy but there is no cure for these disorders.

Narcolepsy following COVID-19: A case report and review of potential mechanisms

Key Clinical Message

The immune activation in COVID-19 may trigger narcolepsy in vulnerable patients. We suggest clinicians carefully evaluate patients with post-COVID fatigue and hypersomnia for primary sleep disorders, specifically narcolepsy.

Abstract

The patient is a 33-year-old Iranian woman without a significant past medical history with the full range of narcolepsy symptoms that started within 2 weeks after her recovery from COVID-19. Sleep studies revealed increased sleep latency and three sleep-onset rapid eye movement events, compatible with a narcolepsy-cataplexy diagnosis.

Novel Objective Measures of Hypersomnolence

Purpose of review

To provide a brief overview of current objective measures of hypersomnolence, discuss proposed measure modifications, and review emerging measures.

Recent findings

There is potential to optimize current tools using novel metrics. High-density and quantitative EEG-based measures may provide discriminative informative. Cognitive testing may quantify cognitive dysfunction common to hypersomnia disorders, particularly in attention, and objectively measure pathologic sleep inertia. Structural and functional neuroimaging studies in narcolepsy type 1 have shown considerable variability but so far implicate both hypothalamic and extra-hypothalamic regions; fewer studies of other CDH have been performed. There is recent renewed interest in pupillometry as a measure of alertness in the evaluation of hypersomnolence.

Summary

No single test captures the full spectrum of disorders and use of multiple measures will likely improve diagnostic precision. Research is needed to identify novel measures and disease-specific biomarkers, and to define combinations of measures optimal for CDH diagnosis.

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.

Temporal distribution of sleep onset REM periods and N3 sleep in the MSLT and night polysomnogram of narcolepsy type 1 and other hypersomnias

INTRODUCTION

The presence of ≥2 sleep onset REM periods (SOREMP) in the Multiple Sleep Latency Test (MSLT) and the previous night polysomnogram (PSG) is part of the diagnostic criteria of narcolepsy, with every SOREMP having the same diagnostic value, despite evidence suggesting that time of SOREMP appearance and their preceding sleep stage might be relevant. We studied the temporal distribution of SOREMPs and associated sleep stages in the MSLT of patients with narcolepsy type 1 (NT1) and other hypersomnias (OH).

METHODS

We reviewed consecutive five-nap MSLTs and their preceding PSG from 83 untreated adult patients with hypersomnolence and ≥1 SOREMPs. Wake/N1(W/N1)-SOREMPs, N2-SOREMPs, and N3 sleep presence and time of appearance were analyzed.

RESULTS

Thirty-nine patients had NT1 and 44 OH. There were 183 (78%) SOREMPs in patients with NT1 and 83 (31%) in OH. Sixty-seven percent of SOREMPs in NT1 were from W/N1, and 20% -none from wake-in OH (p < 0.001). Most patients (94%) with ≥2 W/N1-SOREMPs had NT1 (specificity 95%, sensitivity 82%). In patients with NT1 but not in OH, W/N1-SOREMPs decreased throughout the day (from 79% in the 1st nap to 33% in the preceding night, p < 0.001), whereas N2-SOREMPs did not change. N3 sleep frequency in the 5th nap was higher in NT1 than in OH (28% vs. 7%, p:0.009). Nocturnal-SOREMP plus ≥4 daytime SOREMPs, Wake-REM transitions, and REM followed by N3 were only seen in NT1.

CONCLUSION

Measuring the sleep stage sequence and temporal distribution of SOREMP helps to identify patients with narcolepsy in the MSLT.

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.

A Systematic Review of Sleep–Wake Disorder Diagnostic Criteria Reliability Studies

The aim of this article is to provide a systematic review of reliability studies of the sleep–wake disorder diagnostic criteria of the international classifications used in sleep medicine. Electronic databases (ubMed (1946–2021) and Web of Science (—2021)) were searched up to December 2021 for studies computing the Cohen’s kappa coefficient of diagnostic criteria for the main sleep–wake disorder categories described in the principal classifications. Cohen’s kappa coefficients were extracted for each main sleep–wake disorder category, for each classification subtype, and for the different types of methods used to test the degree of agreement about a diagnosis. The database search identified 383 studies. Fifteen studies were analyzed in this systematic review. Insomnia disorder (10/15) and parasomnia disorder (7/15) diagnostic criteria were the most studied. The reliability of all sleep–wake disorders presented a Cohen’s kappa with substantial agreement (Cohen’s kappa mean = 0.66). The two main reliability methods identified were “test–retest reliability” (11/15), principally used for International Classification of Sleep Disorders (ICSD), and “joint interrater reliability” (4/15), principally used for Diagnostic and Statistical Manual of Mental Disorders (DSM) subtype diagnostic criteria, in particularl, the DSM-5. The implications in terms of the design of the methods used to test the degree of agreement about a diagnosis in sleep medicine are discussed.

The orexin story, sleep and sleep disturbances

The orexins, also known as hypocretins, are two neuropeptides (orexin A and B or hypocretin 1 and 2) produced by a few thousand neurons located in the lateral hypothalamus that were independently discovered by two research groups in 1998. Those two peptides bind two receptors (orexin/hypocretin receptor 1 and receptor 2) that are widely distributed in the brain and involved in the central physiological regulation of sleep and wakefulness, orexin receptor 2 having the major role in the maintenance of arousal. They are also implicated in a multiplicity of other functions, such as reward seeking, energy balance, autonomic regulation and emotional behaviours. The destruction of orexin neurons is responsible for the sleep disorder narcolepsy with cataplexy (type 1) in humans, and a defect of orexin signalling also causes a narcoleptic phenotype in several animal species. Orexin discovery is unprecedented in the history of sleep research, and pharmacological manipulations of orexin may have multiple therapeutic applications. Several orexin receptor antagonists were recently developed as new drugs for insomnia, and orexin agonists may be the next-generation drugs for narcolepsy. Given the broad range of functions of the orexin system, these drugs might also be beneficial for treating various conditions other than sleep disorders in the near future.

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.

50th anniversary of the ESRS in 2022-JSR special issue

This article addresses the clinical presentation, diagnosis, pathophysiology and management of narcolepsy type 1 and 2, with a focus on recent findings. A low level of hypocretin-1/orexin-A in the cerebrospinal fluid is sufficient to diagnose narcolepsy type 1, being a highly specific and sensitive biomarker, and the irreversible loss of hypocretin neurons is responsible for the main symptoms of the disease: sleepiness, cataplexy, sleep-related hallucinations and paralysis, and disrupted nocturnal sleep. The process responsible for the destruction of hypocretin neurons is highly suspected to be autoimmune, or dysimmune. Over the last two decades, remarkable progress has been made for the understanding of these mechanisms that were made possible with the development of new techniques. Conversely, narcolepsy type 2 is a less well-defined disorder, with a variable phenotype and evolution, and few reliable biomarkers discovered so far. There is a dearth of knowledge about this disorder, and its aetiology remains unclear and needs to be further explored. Treatment of narcolepsy is still nowadays only symptomatic, targeting sleepiness, cataplexy and disrupted nocturnal sleep. However, new psychostimulants have been recently developed, and the upcoming arrival of non-peptide hypocretin receptor-2 agonists should be a revolution in the management of this rare sleep disease, and maybe also for disorders beyond narcolepsy.

The diagnostic value of sleep and vigilance tests in central disorders of hypersomnolence

Study Objectives

This retrospective cross-sectional observational study explored the diagnostic value of selected sleep and vigilance tests (SVT) beyond the multiple sleep latency test to differentiate between various central disorders of hypersomnolence (CDH) and fatigue syndromes.

Methods

Data from patients who underwent the multiple sleep latency test and at least one additional SVT were extracted from the Bern sleep database (1997–2018). One thousand three hundred fifty-two patients with a CDH (106 narcolepsy type 1, 90 narcolepsy type 2, 119 idiopathic hypersomnia, 192 nonorganic hypersomnia, 205 insufficient sleep syndrome), fatigue syndromes (n = 183), and a subgroup of patients with sleep apnea (n = 457) were analyzed. Classification based on SVT parameters was compared with the final clinical diagnosis serving as a reference.

Results

An overall model predicted the final diagnosis in 49.5% of patients. However, for the pairwise differentiation of two clinically suspected diagnoses, many SVT parameters showed a sensitivity and specificity above 70%. While the overall discrimination power of the multiple sleep latency test was slightly better than the one of the maintenance of wakefulness test, the latter differentiated best between narcolepsy and idiopathic hypersomnia with prolonged sleep need. Disproportionally poor results in reaction tests (e.g. steer clear test), despite comparable or lower sleepiness levels (SLAT, WLAT), were valuable for differentiating nonorganic hypersomnia from idiopathic hypersomnia/sleep insufficiency syndrome.

Conclusion

This study demonstrates how the combination of a careful clinical assessment and a selection of SVTs can improve the differentiation of CDH, whereas it was not possible to establish an overall prediction model based on SVTs alone.

Self-reported symptoms and objective measures in idiopathic hypersomnia and hypersomnia associated with psychiatric disorders: a prospective cross-sectional study

STUDY OBJECTIVES

In some patients, it is difficult to correctly nosologically classify daytime sleepiness. Clinical manifestations may be nonspecific; on the basis of objective measures it is possible to determine the current severity of sleepiness, but they do not always allow accurate diagnosis. It is especially difficult to distinguish between idiopathic hypersomnia (IH) and hypersomnia associated with a psychiatric disorder (PSY).

METHODS

To find significant differences between the IH and PSY groups, we included 67 patients (IH, n = 15; PSY, n = 52) in the study, focusing on differences in self-reported symptoms, evaluating current depressive symptoms using the Beck Depression Inventory-II score and personality traits measured by the Temperament and Character Inventory. All of the patients underwent polysomnography, the Multiple Sleep Latency Test, and ad libitum sleep monitoring.

RESULTS

The patients with IH showed greater difficulty than those in the PSY group with waking up in the morning (P < .001) and complained of memory (P = .04) and attention deficit (P = .006). They also showed higher total sleep time (P < .001) and sleep efficiency (P = .007) and a shorter mean sleep latency on the Multiple Sleep Latency Test (P < .001). Nevertheless, the IH and PSY groups did not differ in Beck Depression Inventory scores or personality characteristics.

CONCLUSIONS

IH is a syndrome in which depression/external life stressors and personality characteristics also play a role. Patients with IH may benefit from the cooperation of sleep specialists with psychotherapists/psychiatrists.

CITATION

Bušková J, Novák T, Miletínová E, et al. Self-reported symptoms and objective measures in idiopathic hypersomnia and hypersomnia associated with psychiatric disorders: a prospective cross-sectional study. J Clin Sleep Med. 2022;18(3):713-720.

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.

The Psychomotor Vigilance Test as a measure of alertness and sleep inertia in people with central disorders of hypersomnolence

STUDY OBJECTIVES

The central disorders of hypersomnolence (CDH) manifest with daytime sleepiness, often accompanied by cognitive symptoms. Objective tests characterizing cognitive dysfunction may have diagnostic utility. Further, because some people with CDH report worsening cognition upon awakening, cognitive testing before and after napping may provide additional diagnostic information.

METHODS

CDH patients with idiopathic hypersomnia (n = 76), narcolepsy type 1 (n = 19), narcolepsy type 2 (n = 22), and self-reported excessive daytime sleepiness not meeting current diagnostic criteria (n = 76), and non-sleepy controls (n = 33) underwent testing with the psychomotor vigilance test (PVT), a 10-minute reaction time test. A subset of participants underwent repeat testing during a Multiple Sleep Latency Test (MSLT), before and immediately after naps 2 and 4.

RESULTS

Most PVT metrics were significantly better in controls than in patients with CDH. Minimal group differences in PVT performance were observed by CDH diagnosis. PVT performance was weakly correlated to Epworth and MSLT mean sleep latency in the CDH group. Before and after naps, PVT metrics were minimally different for controls, while PVT performance generally worsened following naps in the CDH group, with significant worsening compared to controls for nap 2 mean, median, lapses, and fastest 10% of responses, and nap 4 lapses and slowest 10% of responses. Change in performance did not differ based on CDH diagnostic group for any metric on either nap.

CONCLUSIONS

The PVT, at baseline and following a short nap, may provide adjunctive diagnostic utility in separating individuals with CDH from controls.

Actigraphy prior to Multiple Sleep Latency Test: nighttime total sleep time predicts sleep-onset latency

STUDY OBJECTIVES

To evaluate the clinical utility of actigraphy as compared with sleep questionnaires prior to the Multiple Sleep Latency Test (MSLT) in a sleep disorders clinic population.

METHODS

Twenty-eight clinically referred participants (mean age: 42.3 ± 18.8 years) completed the study protocol. On day 1, participants completed the following questionnaires: Epworth Sleepiness Scale (ESS), Insomnia Severity Index, Pittsburgh Sleep Quality Index (PSQI), Visual Analog Scale (affect, vigor), Patient Health Questionnaire, and Multidimensional Fatigue Symptom Inventory-Short Form. On days 1-8, participants wore an actigraph and completed a sleep diary to assess mean nighttime and mean daytime total sleep time and sleep efficiency or sleep percentage. On day 9, participants repeated the ESS and completed an MSLT. Correlations assessed mean MSLT sleep-onset latency (MSLT-SOL) vs actigraphy, sleep diary, and questionnaires. Chi-square analyses assessed abnormal MSLT-SOL (≤ 8 minutes) or daytime sleepiness (ESS ≥ 10) and referral question (ie, sleep-disordered breathing vs hypersomnolence disorder).

RESULTS

Mean MSLT-SOL was correlated with nighttime total sleep time assessed via both actigraphy and diary, but not with questionnaires. Significant correlations emerged for ESS score on day 1 vs 9, actigraphy vs sleep diary mean nighttime total sleep time, and PSQI vs mean sleep diary sleep efficiency. There was no significant relationship between mean MSLT-SOL and referral question.

CONCLUSIONS

Our finding that total sleep time measured by actigraphy was associated with MSLT-SOL suggests it is useful in informing the interpretation of MSLT findings; however, it does not appear to be a viable substitute for MSLT for the measurement of objective sleepiness in clinical settings.

CITATION

Kelly MR, Zeidler MR, DeCruz S, et al. Actigraphy prior to Multiple Sleep Latency Test: nighttime total sleep time predicts sleep-onset latency. J Clin Sleep Med. 2022;18(1):161-170.

Reliability and Efficacy of the Epworth Sleepiness Scale: Is There Still a Place for It?

The Epworth sleepiness scale (ESS) is a commonly used questionnaire to evaluate patients for excessive daytime sleepiness (EDS). The ESS has been validated as a measure of EDS, but a number of studies have shown more test-retest variability in clinical settings compared to the original validation study. This observation of higher-than-expected test-retest variability has called into question the utility of the ESS as a clinical tool to assess EDS. The purpose of this review article is to summarize how studies of test-retest variability in clinical populations compare to the original validation study of Johns and to highlight where they differ. Furthermore, use of the ESS as a continuous variable (with no specified cutoff value) versus a categorical variable (normal versus high) is described. These observations are put into a clinical context by comparing the test-retest variability observed on the ESS with that of the multiple sleep latency test (MSLT). Finally, how contributors to ESS scores differ within certain subpopulations is described. The ESS remains an important tool to measure EDS in patient populations, but an awareness of its limitations needs to be considered.

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.

Narcolepsy with intermediate cerebrospinal level of hypocretin-1

STUDY OBJECTIVES

To describe the phenotype of narcolepsy with intermediate cerebrospinal hypocretin-1 levels (CSF hcrt-1).

METHODS

From 1600 consecutive patients with narcolepsy from Bologna and Montpellier sleep centers we selected patients with intermediate CSF hcrt-1 levels (110-200 pg/ml). Clinical, neurophysiological and biological data were contrasted for the presence of cataplexy, HLA-DQB1*06:02, and median CSF hcrt-1 levels (149.34 pg/mL).

RESULTS

Forty-five (55% males, aged 35 ± 17 years) patients (2.8% of all cases) were included. Thirty-three (73%) were HLA-DQB1*06:02, 29 (64%) reported cataplexy (21, 72.4% with typical features), and 5 (11%) had presumed secondary etiology. Cataplexy was associated with other core narcolepsy symptoms, increased sleep onset REM periods, and nocturnal sleep disruption. Cataplexy and irrepressible daytime sleep were more frequent in HLA DQB1*06:02 positive patients. Lower CSF hcrt-1 levels were associated with hallucinations.

CONCLUSION

Narcolepsy with intermediate CSF hcrt-1 level is a rare condition with heterogeneous phenotype. HLA DQB1*06:02 and lower CSF hcrt-1 were associated with typical narcolepsy features, calling for future research to distinguish incomplete from secondary narcolepsy forms.

Differential characteristics of repeated polysomnography and multiple sleep latency test parameters in narcolepsy type 1 and type 2 patients: a longitudinal retrospective study

PURPOSE

Narcolepsy is a chronic disorder and its phenotype is dichotomized into narcolepsy type 1 (NT1) and narcolepsy type 2 (NT2). The clinical course and pathophysiological mechanisms of these two clinical entities and their differences are not adequately defined. This study aimed to explore the differential longitudinal patterns of polysomnography (PSG) and multiple sleep latency test (MSLT) in NT1 and NT2.

METHODS

In this retrospective study demographic characteristics, PSG, and MSLT parameters at baseline and follow-up were compared between NT1 and NT2 patients. Patients with both follow-up MSLT and PSG were selected for sub-group analysis. Baseline and follow-up MSLT and PSG parameters were compared.

RESULTS

Of 55 patients with narcolepsy, mean follow-up periods were 7.4 ± 3.5 years for NT1 and 5.5 ± 2.9 for NT2. Demographic data showed increased body mass index and prevalence of sleep paralysis in NT1. Baseline PSG characteristics between NT1 and NT2 showed decreased sleep latency (p = 0.016) and REM latency (p = 0.046) in NT1 group when compared with NT2. Nocturnal SOREMP on PSG was more prevalent in NT1 (p = 0.017), and half of NT2 patients with nocturnal SOREMP on PSG changed their diagnoses to NT1. On follow-up PSG, NT1 displayed reductions in sleep stage N2 (p = 0.006) and N3 (p = 0.048), while wake after sleep onset (WASO) (p = 0.023) and apnea-hypopnea index (AHI) (p = 0.007) were significantly increased.

CONCLUSION

Differential MSLT and PSG characteristics of NT1 and NT2 in at baseline and follow-up indicate that NT1 and NT2 are distinct disease phenotypes, and that they present with a contrasting course of disease.

Stability of nocturnal wake and sleep stages defines central nervous system disorders of hypersomnolence

STUDY OBJECTIVES

We determine if young people with narcolepsy type 1 (NT1), narcolepsy type 2 (NT2), and idiopathic hypersomnia (IH) have distinct nocturnal sleep stability phenotypes compared to subjectively sleepy controls.

METHODS

Participants were 5- to 21-year old and drug-naïve or drug free: NT1 (n = 46), NT2 (n = 12), IH (n = 18), and subjectively sleepy controls (n = 48). We compared the following sleep stability measures from polysomnogram recording between each hypersomnolence disorder to subjectively sleepy controls: number of wake and sleep stage bouts, Kaplan-Meier survival curves for wake and sleep stages, and median bout durations.

RESULTS

Compared to the subjectively sleepy control group, NT1 participants had more bouts of wake and all sleep stages (p ≤ .005) except stage N3. NT1 participants had worse survival of nocturnal wake, stage N2, and rapid eye movement (REM) bouts (p < .005). In the first 8 hours of sleep, NT1 participants had longer stage N1 bouts but shorter REM (all ps < .004). IH participants had a similar number of bouts but better survival of stage N2 bouts (p = .001), and shorter stage N3 bouts in the first 8 hours of sleep (p = .003). In contrast, NT2 participants showed better stage N1 bout survival (p = .006) and longer stage N1 bouts (p = .02).

CONCLUSIONS

NT1, NT2, and IH have unique sleep physiology compared to subjectively sleepy controls, with only NT1 demonstrating clear nocturnal wake and sleep instability. Overall, sleep stability measures may aid in diagnoses and management of these central nervous system disorders of hypersomnolence.

Cerebrospinal fluid monoamine levels in central disorders of hypersomnolence

STUDY OBJECTIVES

Whether the cause of daytime sleepiness in narcolepsy type 1 (NT1) is a direct consequence of the loss of orexin (ORX) neurons or whether low orexin reduces the efficacy of the monoaminergic systems to promote wakefulness is unclear. The neurobiology underlying sleepiness in other central hypersomnolence disorders, narcolepsy type 2 (NT2), and idiopathic hypersomnia (IH), is currently unknown.

METHODS

Eleven biogenic amines including the monoaminergic neurotransmitters and their metabolites and five trace amines were measured in the cerebrospinal fluid (CSF) of 94 drug-free subjects evaluated at the French National Reference Center for Narcolepsy: 39 NT1(orexin-deficient) patients, 31 patients with objective sleepiness non orexin-deficient (NT2 and IH), and 24 patients without objective sleepiness.

RESULTS

Three trace amines were undetectable in the sample: tryptamine, octopamine, and 3-iodothyronamine. No significant differences were found among the three groups for quantified monoamines and their metabolites in crude and adjusted models; however, CSF 5-hydroxyindoleacetic acid (5-HIAA) levels tended to increase in NT1 compared to other patients after adjustment. Most of the biomarkers were not associated with ORX-A levels, clinical or neurophysiological parameters, but a few biomarkers (e.g. 3-methoxy-4-hydroxyphenylglycol and norepinephrine) correlated with daytime sleepiness and high rapid eye movement (REM) sleep propensity.

CONCLUSIONS

We found no striking differences among CSF monoamines, their metabolites and trace amine levels, and few associations between them and key clinical or neurophysiological parameters in NT1, NT2/IH, and patients without objective sleepiness. Although mostly negative, these findings are a significant contribution to our understanding of the neurobiology of hypersomnolence in these disorders that remain mysterious and deserve further exploration.

Diagnostic value of actigraphy in hypersomnolence disorders

OBJECTIVE

Differentiating between the central hypersomnias presents a challenge to the diagnosis of patients with hypersomnolence. Actitigraphy may support efforts to distinguish them. We aimed to evaluate: 1) the ability of actigraphy to quantify sleep continuity measures in comparison with polysomnography in patients with hypersomnolence; 2) whether actigraphy can distinguish patients with hypersomnolence with normal hypocretin-1 in cerebrospinal fluid from patients with narcolepsy type 1 and from sleep-healthy controls; and 3) the distinct activity profiles and circadian rhythms of patients with narcolepsy type 1, patients with hypersomnolence with normal hypocretin-1 in cerebrospinal fluid, and sleep-healthy controls.

METHOD

Polysomnography, multiple sleep latency tests and actigraphy were conducted in 14 patients with narcolepsy type 1, 29 patients with hypersomnolence with normal hypocretin-1 in cerebrospinal fluid and 15 sleep-healthy controls.

RESULTS

Actigraphy quantified several sleep continuity measures consistently with polysomnography in all the patients. Actigraphy distinguished patients with hypersomnolence with normal hypocretin-1 in cerebrospinal fluid from patients with narcolepsy type 1 and sleep-healthy controls. Patients with narcolepsy type 1 had poor sleep quality and altered circadian rest-activity rhythm compared with controls.

CONCLUSION

Actigraphy is an adequate tool for establishing the amount of night sleep and supports the differential diagnosis of patients with hypersomnolence.

Multimodal assessment increases objective identification of hypersomnolence in patients referred for multiple sleep latency testing

STUDY OBJECTIVES

The multiple sleep latency test (MSLT) has limitations when evaluating disorders of hypersomnolence with unknown etiology. Alternative measures of hypersomnolence may objectively identify pathology in patients with complaints of daytime sleepiness that may not be captured by the MSLT alone. This study evaluated the impact of a multimodal hypersomnolence assessment relative to MSLT in patients with unexplained hypersomnolence.

METHODS

Seventy-five patients with unexplained hypersomnolence were included in the analyzed sample. Polysomnography was performed without prescribed wake time, and the psychomotor vigilance task and pupillographic sleepiness test were completed between MSLT nap opportunities. Presence or absence of hypersomnolence for each assessment was defined using a priori cutpoints. Proportions of patients identified as hypersomnolent using the multimodal assessment relative to MSLT alone were evaluated, as well as the sensitivity and specificity of ancillary hypersomnolence measures relative to MSLT as a gold standard.

RESULTS

The multimodal assessment more than doubled the proportion of patients identified as having objective deficits relative to MSLT ≤ 8 minutes alone. The combination of excessive sleep duration, lapses on the psychomotor vigilance task, and impairments on the pupillographic sleepiness test also had perfect sensitivity in identifying all patients identified as sleepy by the MSLT across 3 different MSLT cutpoints (5, 8, and 10 minutes).

CONCLUSIONS

These data demonstrate the insufficiency of the MSLT as a singular tool to identify objective pathology in persons with unexplained hypersomnolence. Further efforts to refine and standardize multimodal assessments will likely improve diagnostic acumen and research into the causes of these disorders.

PAX8/PAX8-AS1 DNA methylation levels are associated with objective sleep duration in persons with unexplained hypersomnolence using a deep phenotyping approach

STUDY OBJECTIVES

Patients with unexplained hypersomnolence have significant impairment related to daytime sleepiness and excessive sleep duration, the biological bases of which are poorly understood. This investigation sought to examine relationships between objectively measured hypersomnolence phenotypes and epigenetic modification of candidate hypersomnolence genes to advance this line of inquiry.

METHODS

Twenty-eight unmedicated clinical patients with unexplained hypersomnolence were evaluated using overnight ad libitum polysomnography, multiple sleep latency testing, infrared pupillometry, and the psychomotor vigilance task. DNA methylation levels on CpG sites annotated to 11 a priori hypersomnolence candidate genes were assessed for statistical association with hypersomnolence measures using independent regression models with adjusted local index of significance (aLIS) P-value threshold of 0.05.

RESULTS

Nine CpG sites exhibited significant associations between DNA methylation levels and total sleep time measured using ad libitum polysomnography (aLIS p-value < .05). All nine differentially methylated CpG sites were annotated to the paired box 8 (PAX8) gene and its related antisense gene (PAX8-AS1). Among these nine differentially methylated positions was a cluster of five CpG sites located in the body of the PAX8 gene and promoter of PAX8-AS1.

CONCLUSIONS

This study demonstrates that PAX8/PAX8-AS1 DNA methylation levels are associated with total sleep time in persons with unexplained hypersomnolence. Given prior investigations that have implicated single nucleotide polymorphisms in PAX8/PAX8-AS1 with habitual sleep duration, further research that clarifies the role of DNA methylation levels on these genes in the phenotypic expression of total sleep time is warranted.

Cortical arousal frequency is increased in narcolepsy type 1

STUDY OBJECTIVES

Hypocretin deficient narcolepsy (type 1, NT1) presents with multiple sleep abnormalities including sleep-onset rapid eye movement (REM) periods (SOREMPs) and sleep fragmentation. We hypothesized that cortical arousals, as scored by an automatic detector, are elevated in NT1 and narcolepsy type 2 (NT2) patients as compared to control subjects.

METHODS

We analyzed nocturnal polysomnography (PSG) recordings from 25 NT1 patients, 20 NT2 patients, 18 clinical control subjects (CC, suspected central hypersomnia but with normal cerebrospinal (CSF) fluid hypocretin-1 (hcrt-1) levels and normal results on the multiple sleep latency test), and 37 healthy control (HC) subjects. Arousals were automatically scored using Multimodal Arousal Detector (MAD), a previously validated automatic wakefulness and arousal detector. Multiple linear regressions were used to compare arousal index (ArI) distributions across groups. Comparisons were corrected for age, sex, body-mass index, medication, apnea-hypopnea index, periodic leg movement index, and comorbid rapid eye movement sleep behavior disorder.

RESULTS

NT1 was associated with an average increase in ArI of 4.02 events/h (p = 0.0246) compared to HC and CC, while no difference was found between NT2 and control groups. Additionally, a low CSF hcrt-1 level was predictive of increased ArI in all the CC, NT2, and NT1 groups.

CONCLUSIONS

The results further support the hypothesis that a loss of hypocretin neurons causes fragmented sleep, which can be measured as an increased ArI as scored by the MAD.

Characteristics associated with hypersomnia and excessive daytime sleepiness identified by extended polysomnography recording

STUDY OBJECTIVES

Hypersomnolence, defined by excessive daytime sleepiness (EDS) or excessive quantity of sleep (EQS), has been associated with increased morbidity. The aim of this study was to determine the clinical and polysomnographic characteristics associated with EQS and EDS assessed objectively during extended polysomnography recording.

METHODS

A total of 266 drug-free subjects (201 women; mean age: 26.5 years [16.08; 60.87]) underwent 32-h bed-rest polysomnography recording preceded by polysomnography and modified multiple sleep latency test (mMSLT). Participants were categorized according to their total sleep time (bed-rest TST ≥19 h, hypersomnia), objective EDS (mean sleep latency on MSLT ≤8 min), and self-reported EDS (Epworth sleepiness scale score >10) and EQS (≥9 h/24 h per week).

RESULTS

Subjects with hypersomnia were often younger, with normal sleep architecture, high nighttime sleep efficiency, and severe objective EDS. No association with sex, body mass index, Epworth sleepiness scale, EQS, and depressive symptoms was detected. Subjects with objective EDS had less EQS, higher sleep efficiency, and increased hypersomnia. Discrepancies were observed between objective and self-reported measures of sleep duration and EDS. Finally, 71 subjects were identified who had objective hypersomnia and/or EDS, no medical and psychiatric conditions and normal polysomnography parameters, and therefore met the stringent criteria of idiopathic hypersomnia, an orphan disorder.

CONCLUSIONS

Sleep duration and EDS should be quantified using self-reported and objective measures in a controlled procedure to differentiate long sleepers, patients with hypersomnia, and patients with idiopathic hypersomnia. This will help to better understand their biology, to identify specific biomarkers, and to assess related health outcomes.

Environmental factors related to sleep latency among inpatients in rehabilitation wards according to functional independence measure cognitive scores

BACKGROUND

No study has investigated sleep-related environmental factors in patients according to their functional independence measure (FIM) cognitive scores.

AIMS

The aim of this study is to examine the associations between environmental factors such as noise and sleep latency according to the FIM cognitive scores among inpatients in rehabilitation wards.

DESIGN

This is a prospective longitudinal study.

METHODS

This study measured the sleep state using a bed-based actigraphy, environmental data from Environmental Sensor®, and medical record information of 33 inpatients in the rehabilitation wards during 2018. A linear mixed-effect model was used to analyse the associations between sleep latency and environmental factors. Participants were grouped according to high or low FIM cognitive scores.

RESULTS

The average patient age was 77.2 ± 10.9 years, and 48.5% were male. In the high FIM cognitive score group, the loudness and frequency of noise exceeding 40 dB during sleep latency were significantly associated with sleep latency. In the low FIM cognitive score group, only the noise frequency was associated with sleep latency, and intra-individual variance was larger than that of the high group.

CONCLUSION

These findings suggest that providing night care with attention to subdued noise is important, particularly for patients with low cognitive functional independence levels measured by the FIM cognitive score.

To split or to lump? Classifying the central disorders of hypersomnolence

The classification of the central disorders of hypersomnolence has undergone multiple iterations in an attempt to capture biologically meaningful disease entities in the absence of known pathophysiology. Accumulating data suggests that further refinements may be necessary. At the 7th International Symposium on Narcolepsy, a group of clinician-scientists evaluated data in support of keeping or changing classifications, and as a result suggest several changes. First, idiopathic hypersomnia with long sleep durations appears to be an identifiable and meaningful disease subtype. Second, idiopathic hypersomnia without long sleep time and narcolepsy without cataplexy share substantial phenotypic overlap and cannot reliably be distinguished with current testing, and so combining them into a single disease entity seems warranted at present. Moving forward, it is critical to phenotype patients across a wide variety of clinical and biological features, to aid in future refinements of disease classification.

2018 worldwide survey of health-care providers caring for patients with narcolepsy: WSS narcolepsy task force

BACKGROUND

There are limited data available on regional differences in the diagnosis and management of narcolepsy. In order to better understand worldwide trends in clinical assessment and management of narcolepsy, a survey of health-care providers was conducted by the World Sleep Society Narcolepsy task force.

METHODS

A total of 146 surveys that included items on the diagnosis and management of narcolepsy were completed by practitioners representing 37 countries.

RESULTS

Most of the participants were from Europe, North America, Oceania, Asia and Latin America. A consistent approach to applying the diagnostic criteria of Narcolepsy was documented with the exception of measurement of CSF hypocretin-1, which has limited availability. While the majority of practitioners (58%) reported not using the test, 1% indicated always evaluating CSF hypocretin-1 levels. There was much variability in the availability of currently recommended medications such as sodium oxybate and pitolisant; modafinil and antidepressants were the most commonly used medications. Amphetamines were unavailable in some countries.

CONCLUSION

The results of the study highlight clinical and therapeutic realities confronted by worldwide physicians in the management of narcolepsy. While the diagnostic criteria of narcolepsy rely in part on the quantification of CSF hypocretin-1, few physicians reported having incorporated this test into their routine assessment of the condition. Regional differences in the management of narcolepsy appeared to be related to geographic availability and expense of the therapeutic agents.

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.

Diagnosing narcolepsy in the active duty military population

PURPOSE

Narcolepsy type I and type II are central hypersomnias characterized by excessive daytime sleepiness and nocturnal sleep disruptions. These rare disorders make the diagnosis complex, as multiple sleep disorders are known to cause false-positive results on testing. There is a high incidence of sleep disorders in the military, and the diagnosis of narcolepsy can have serious career implications. This study looked to assess for the presence of confounding disorders in patients previously diagnosed with narcolepsy.

METHODS

We conducted a retrospective analysis of patients aged 18-65 previously diagnosed with narcolepsy at an outside facility, referred for repeat evaluation at the Wilford Hall Sleep Disorders Center. Previous test results from the time of original diagnosis were reviewed if available and compared with repeat evaluation which included actigraphy, in-laboratory polysomnography, and multiple sleep latency testing.

RESULTS

Of the 23 patients, 2 (9%) retained a diagnosis of narcolepsy after repeat testing. Ten patients (43%) had insufficient sleep syndrome, five (22%) had significant circadian rhythm sleep-wake disorders, and nine (39%) patients were diagnosed with mild obstructive sleep apnea (OSA). Four of the nine patients with OSA (44%) had supine predominant OSA.

CONCLUSION

Diagnostic testing for narcolepsy may be influenced by the presence of comorbid sleep disorders including sleep-disordered breathing, insufficient sleep duration, and circadian misalignment which are common in active military personnel. This study emphasizes the importance of excluding these comorbid diagnoses in this population.