Idling for Decades: A European Study on Risk Factors Associated with the Delay Before a Narcolepsy Diagnosis

Clinical challenges in narcolepsy: From delayed diagnosis to daytime function impairments during treatment

OBJECTIVE

While a delayed diagnosis of narcolepsy is common, the reasons are not well understood. Additionally, only few systematic studies have focused on the daytime function of treated patients. In this cross-sectional online survey, we aimed to investigate the predictive factors for diagnostic delays and daytime dysfunction in Japanese patients with narcolepsy undergoing treatment.

METHOD

This survey included individuals aged 16 years or older with a confirmed diagnosis of narcolepsy. The participants completed a questionnaire related to disease diagnosis and current daytime function, including quality of life measured with Short Form-8 (SF-8) and work performance measured with the Work Productivity and Activity Impairment (WPAI) questionnaire.

RESULTS

The study enrolled 248 of the 250 respondents. The mean time from symptom onset to definitive diagnosis was 8.7 years. Diagnostic delay was significantly associated with the year of symptom onset (<2005 vs. ≥2005), age at symptom onset (<16 vs. ≥16 years), narcolepsy type (without or with cataplexy), residence (rural vs. urban), and information sources about the disorder. The participants had a lower mental component summary score in SF-8 and higher WPAI absenteeism, presenteeism, and overall work impairment scores than the general Japanese population. Severe daytime sleepiness (Epworth Sleepiness Scale score ≥16) and younger age were associated with a poor mental component summary score and higher presenteeism and overall work impairment.

CONCLUSIONS

Improving sleepiness is crucial to optimize the patients' daytime functioning. A treatment system that addresses regional disparities in narcolepsy care is needed, along with increased public awareness, especially in educational settings.

Sex effect on time to diagnosis and clinical features of narcolepsy type 1 and 2

STUDY OBJECTIVES

Sex influences sleep through physiological differences and impacts the clinical presentation and quality of life in patients with sleep disorders. However, there is a paucity of evidence regarding differences between men and women affected by narcolepsy. This study aimed to explore the sex-based dissimilarities in time to diagnosis and clinical features in narcolepsy.

METHODS

This retrospective observational study included adult patients with narcolepsy type 1 (NT1) and type 2 (NT2). Clinical, polysomnographic, and biofluid parameters were compared between men and women.

RESULTS

The study analyzed 42 patients: 27 with NT1 (64.3 %) and 15 with NT2 (35.7 %). Among these, 18 were male (42.9 %; mean age 34.72 ± 12.89 years) and 24 were female (57.1 %; mean age 37.96 ± 13.2 years). No significant sex differences were observed in the age at onset of symptoms. Notably, females had significantly longer diagnostic delay compared to males (p = 0.04) and a higher rate of misdiagnosis before receiving the diagnosis of narcolepsy (p < 0.001). Male patients exhibited significantly longer stage 2 of Non-REM sleep percentage compared to females patients (p = 0.024). There were no significant differences in psychiatric comorbidities (p = 0.30).

CONCLUSIONS

Women with narcolepsy experience longer time to obtain the correct diagnosis and are more frequently misdiagnosed with other disorders compared to men. The present findings highlight a potential sex-based disparity in diagnostic practices that may negatively impact the well-being of women with narcolepsy, as their symptoms are more commonly misdiagnosed.

Daytime sleepiness and BMI exhibit gender and age differences in patients with central disorders of hypersomnolence

The aim of the present study was to examine gender and age-specific effects on subjective daytime sleepiness (as measured by the Epworth Sleepiness Scale), body weight and eating behaviour in patients with central disorders of hypersomnolence. Based on the European Narcolepsy Network database, we compared 1035 patients with narcolepsy type I and 505 patients with other central disorders of hypersomnolence ("narcoleptic borderland"), including narcolepsy type II (N = 308) and idiopathic hypersomnia (N = 174), using logistic regression and general linear models. In the entire study population, the Epworth Sleepiness Scale was higher in women (N = 735, mean age = 30 years, mean Epworth Sleepiness Scale = 16.6 ± SD 3.9) than in men (N = 805, mean age = 32 years, mean Epworth Sleepiness Scale = 15.8 ± SD 4.4). In women with narcolepsy type I (N = 475), both Epworth Sleepiness Scale and body mass index increased in parallel with age. In women of the narcoleptic borderland (N = 260), the Epworth Sleepiness Scale markedly peaked in their early 30s, while body mass index only started to rise at that age. This rise in body mass index following the Epworth Sleepiness Scale peak cannot be explained by sleepiness-induced uncontrolled eating, as self-reported uncontrolled eating was negatively associated with the Epworth Sleepiness Scale in this group. We propose that the narcoleptic borderland harbours a unique cluster of women in their fertile years with an unexplored aetiology requiring further investigation towards tailored interventions.

Prevalence of narcolepsy in representative samples of the general population of North America, Europe, and South Korea

OBJECTIVES

Narcolepsy is a rare, chronic, central disorder of hypersomnolence characterized by excessive daytime sleepiness, hypnagogic/hypnopompic hallucinations, sleep paralysis, disrupted nighttime sleep, and sometimes cataplexy (Type 1). The objective of this study was to assess the prevalence of narcolepsy in a large representative general population sample in North America, Europe, and Asia.

METHODS

This cross-sectional epidemiological study utilized data from the Sleep-EVAL research database. The study involved 61,754 participants from 10 countries interviewed between 1992 and 2016 using the Sleep-EVAL Expert System, an artificial intelligence system designed to conduct interviews and perform positive and differential diagnoses based on interview responses. Using the answers provided for each symptom, the expert system built its diagnostic tree to reach a diagnostic conclusion of narcolepsy type 1 (NT1) or narcolepsy type 2 (NT2) for each participant according to the International Classification of Sleep Disorders, Third Edition, criteria.

RESULTS

Overall, the prevalence of NT1 was estimated to be 19.1/100,000 persons and the prevalence of NT2 was 23.3/100,000 persons. Prevalence of NT1 and NT2 was similar between countries and between men and women. Highest prevalence was among participants aged 35 years or younger for NT1 and among participants aged 35-54 years for NT2.

CONCLUSIONS

Our study, based on data from the general populations of several countries, shows that narcolepsy is a rare disorder, affecting 42.4/100,000 persons.

Clinical and objective correlates of disrupted nighttime sleep in pediatric narcolepsy type 1

OBJECTIVES

Disrupted nocturnal sleep (DNS) is a common symptom in Narcolepsy type 1 (NT1) but remains understudied in pediatric populations. We aimed to identify factors associated with DNS complaint in children with NT1, and to evaluate treatment effect on this symptom.

METHODS

Eighty-seven consecutive NT1 children (14 ± 2.8y.o., 68 untreated), diagnosed according to ICSD3-TR criteria, underwent standardized evaluations with recording of clinical characteristics, self-questionnaires including the Pediatric-Narcolepsy Severity Scale (NSS-P), polysomnography (PSG), multiple sleep latency tests, and CSF orexin-A levels measurments. Among untreated patients, 41 were reevaluated after stable management. DNS was assessed using a single NSS-P item and categorized as absent/mild versus moderate/severe.

RESULTS

In the cross-sectional sample, 68 % untreated children reported DNS (mild, moderate or severe) on NSS-P. Untreated children with moderate/severe DNS (37 %) had higher NSS-P scores, more hallucinations, REM sleep parasomnias, insomnia and fatigue. In untreated patients, on PSG, higher indexes of periodic legs movements during sleep and microarousal were associated with DNS complaint. In the longitudinal sample, DNS improved in 34 % of all treated children: NSS-P scores and depressive and insomnia symptoms decreased, with less fragmented sleep on PSG (i.e. sleep/wake bouts, transitions, Wake/N1 indexes). However, no associations were found between DNS improvement, and clinical and PSG features.

CONCLUSION

DNS complaint in pediatric NT1 is frequent, associated with disease severity, but with few PSG markers in untreated condition. It improves in one third of patients after management. Further studies are needed to determine optimal measures of DNS in narcolepsy across ages, to be implemented in the management strategy.

Measuring energy expenditure in narcolepsy using doubly labeled water and respiration chamber calorimetry

STUDY OBJECTIVES

Hypocretin deficiency causes type 1 narcolepsy, a condition characterized by excessive daytime sleepiness, cataplexy, and fragmented nocturnal sleep. Two-thirds of people with narcolepsy are also overweight, of which half are obese. The pathophysiology behind weight gain in people with narcolepsy remains unknown. We assessed a possible decrease in energy expenditure as a cause for overweight in narcolepsy using respiration chamber calorimetry and doubly labeled water.

METHODS

Ten males with type I narcolepsy and nine matched (for age, sex, and BMI) healthy controls were enrolled. Participants stayed in a respiration chamber for 24 hours. They subsequently received doubly labeled water and wore an accelerometer for 2 weeks to assess energy expenditure and physical activity under daily living conditions. Total daily energy expenditure, resting energy expenditure (REE), overnight metabolic rate, physical activity level, and activity-induced energy expenditure were measured.

RESULTS

No significant differences were found in REE, mean 24-hour respiration chamber energy expenditure, overnight metabolic rate, and activity-induced energy expenditure when comparing people with narcolepsy type 1 to controls. Physical activity was also comparable between groups.

CONCLUSIONS

Energy expenditure in narcolepsy type 1 is similar to matched controls, suggesting comparable metabolism and physical activity rates. It remains possible that metabolic changes are most pronounced around disease onset. In addition, patients had to discontinue their medication which may have influenced the results. Still, our findings suggest that other factors may also play a role in weight gain in narcolepsy, such as differences in dietary behavior.

Use of Portable 24-Hour Polysomnography as Alternative Diagnostic Tool for Narcolepsy Type 1 in Adults and Children

BACKGROUND AND OBJECTIVES

The diagnosis of narcolepsy type 1 (NT1) currently requires the multiple sleep latency test (MSLT), or a nocturnal sleep-onset REM period (SOREMP) combined with typical cataplexy, or alternatively the determination of CSF hypocretin-1 (CSF-hcrt-1) deficiency. We evaluated the 24-hour polysomnography (PSG) recordings in adult and pediatric patients as an alternative diagnostic tool.

METHODS

Patients of any age, referred to the narcolepsy center of a university hospital for suspected central disorder of hypersomnolence (CDH), were consecutively recruited between 2013 and 2022. Participants underwent 2 days (day1-night1-day2-night2) of continuous dynamic PSG followed by MSLT. When consent was given, CSF-hcrt-1 was measured. The accuracy of 24-hour PSG variables from night1 and day2 (index test) was assessed with receiver operating characteristic (ROC) curve analysis in identifying NT1 based on current criteria (applied to night2-PSG, MSLT, and CSF-hcrt1). The markers with area under the curve (AUC) ≥0.75 were then tested in adults and children, separately, and to diagnose NT1 and narcolepsy type 2 (NT2) in different scenarios.

RESULTS

Eight hundred seven patients (30.1% pediatric, 52.4% male) were included, and 709 had CSF-hcrt-1 measured. According to the standard criteria, 322 were diagnosed with NT1 (mean age 26.7 ± 17.1 years, 40.4% pediatric, 54.0% male) and 484 with non-NT1 (mean age 32.7 ± 16.5 years, 23.3% pediatric, 51.3% male), encompassing 31 with NT2, 163 with idiopathic hypersomnia, and 281 with other diagnoses. Detecting SOREMP ≥1 during daytime resulted in AUC = 0.84 (95% CI 0.82-0.87), with 84.4% sensitivity and 84.5% specificity for NT1. Performance was superior to all nighttime-PSG measures (p < 0.001) including nighttime-SOREMP (AUC = 0.77, 95% CI 0.74-0.80; sensitivity = 62.1%, specificity = 91.7%) and did not differ from 24-hour SOREMP ≥1 (AUC = 0.85, 95% CI 0.82-0.87; sensitivity = 89.7%, specificity = 80.2%). The combination of daytime-SOREMP ≥1 with cataplexy showed AUC = 0.89 (95% CI 0.86-0.91) for NT1, superior to the combination of nighttime-SOREMP with cataplexy (AUC = 0.78, 95% CI 0.76-0.81, p < 0.001) and similar to MSLT criteria for narcolepsy (AUC = 0.90, 95% CI 0.88-0.92, p = 0.36). Performances were similar in adults and children. Daytime-SOREMP ≥1 identified NT1 and NT2 combined within all CDH with a sensitivity of 80.8% and specificity of 88.0%.

CONCLUSIONS

The detection of daytime-SOREMP during dynamic 24-hour PSG is more accurate than nighttime-SOREMP for diagnosing narcolepsy and, combined with cataplexy, is comparable with MSLT criteria for the identification of NT1. These results offer the prospect of 24-hour PSG diagnostics for NT1 in the home setting.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that daytime SOREMP during a 24-hour PSG accurately distinguishes NT1 in patients with a clinical history of possible cataplexy from those who do not have NT1.

Families of adults with idiopathic hypersomnia and narcolepsy: psychosocial impact and contribution to symptom management

STUDY OBJECTIVES

This study examined the impact of central disorders of hypersomnolence (CDH) on family members of adult patients, the ways family members assist with managing CDH, and family members' utilization and satisfaction with information and support.

METHODS

Participants were adults (n = 100) with an adult family member diagnosed with idiopathic hypersomnia or narcolepsy. They completed a survey which included the Family Reported Outcome Measure, checklists, satisfaction ratings, and open-response questions.

RESULTS

The Family Reported Outcome Measure sample mean (14.2, standard deviation = 6.8) corresponded to a moderate effect on quality of life. Compared to parents, partners reported a higher impact on the personal and social life domain (P = .04, d = .44). The most frequently endorsed sources of support were family (60.0%) and friends (50.0%), whereas information was most commonly obtained from hypersomnia organizations (69.0%) and medical professionals (61.0%). Only 8.0% of participants were satisfied with support, and 9.0% were satisfied with information. Participants endorsed assisting with managing CDH, such as picking up prescriptions (61.0%), attending medical visits (50.0%), reminding to take medication (48.0%), and coordinating medical care (39.0%). Qualitative data indicated that relationships underwent a transformation from conflict and confusion (prediagnosis) to clarity (postdiagnosis), followed by adjusting expectations. Caregiving strain, effects on shared activities, and negative psychosocial impacts on family also emerged as themes.

CONCLUSIONS

Family members play an important role in supporting adults with CDH in many ways, including tasks related to managing CDH. Family members experience many psychosocial impacts from CDH, and data from this study indicate unmet needs for support.

CITATION

Mundt JM, Franklin R-C, Horsnell M, Garza V. Families of adults with idiopathic hypersomnia and narcolepsy: psychosocial impact and contribution to symptom management. J Clin Sleep Med. 2025;21(4):683-694.

What is it like to live with narcolepsy? A scoping review

BACKGROUND

Narcolepsy impacts quality of life (QoL) with its symptomatology in hobbies and everyday activities, work and productivity and has social and economic consequences. The aim of this review is to map and synthesize evidence about QoL in narcolepsy patients and to focus on research strategies and publications in the matter.

METHODS

A scoping review of articles published between 2014-2025. The initial search of WoS resulted in 7748 articles and 2583 in PubMed being screened for eligibility. Intervention, comorbidity, non-narcolepsy, prevalence and medical trials studies were excluded. We extracted data on bibliometric characteristics, research questions, sample and recruitment method, design, concepts and measures, and the main findings. Two independent reviewers did the screening and analyses. The analyzed data were consulted on with stakeholders to settle gaps, possibilities and directions for future research. This study followed the PRISMA-ScR guidelines.

RESULTS

Twenty papers were included in this study. There is an increasing trend in publishing studies focused on QoL in narcolepsy patients, but its spread is very limited across various audiences. Most of the studies assess the association of narcolepsy symptoms, treatment, mental health or nutritional status and QoL in narcolepsy patients. Most used was a questionnaire-based cross-sectional design comparing a control group vs narcolepsy patients recruited through regular follow up at a sleep clinic or national reference centers or patients' organization.

CONCLUSION

There is a need to spread knowledge beyond the neurology audience, to widen the scope of research beyond the burden of the symptoms and to employ explorative qualitative designs.

Trends in Prescription of Stimulants and Narcoleptic Drugs in Switzerland: Longitudinal Health Insurance Claims Analysis for the Years 2014-2021

Background

Stimulants are potent treatments for central hypersomnolence disorders or attention-deficit/hyperactivity disorders/attention deficit disorders but concerns have been raised about their potential negative consequences and their increasing prescription rates.

Objective

We aimed to describe stimulant prescription trends in Switzerland from 2014 to 2021. Second, we aimed to analyze the characteristics of individuals who received stimulant prescriptions in 2021 and investigate the link between stimulant prescriptions and hospitalization rates in 2021, using hospitalization as a potential indicator of adverse health outcomes.

Methods

Longitudinal and cross-sectional data from a large Swiss health care insurance were analyzed from all insureds older than 6 years. The results were extrapolated to the Swiss general population. We identified prescriptions for methylphenidate, lisdexamfetamine, modafinil, and sodium oxybate and calculated prevalences of each drug prescription over the period from 2014 to 2021. For 2021 we provide detailed information on the prescribers and evaluate the association of stimulant prescription and the number and duration of hospitalization using logistic regression models.

Results

We observed increasing prescription rates of all stimulants in all age groups from 2014 to 2021 (0.55% to 0.81%, 43,848 to 66,113 insureds with a prescription). In 2021, 37.1% (28,057 prescriptions) of the medications were prescribed by psychiatrists, followed by 36.1% (n=27,323) prescribed by general practitioners and 1% (n=748) by neurologists. Only sodium oxybate, which is highly specific for narcolepsy treatment, was most frequently prescribed by neurologists (27.8%, 37 prescriptions). Comorbid psychiatric disorders were common in patients receiving stimulants. Patients hospitalized in a psychiatric institution were 5.3 times (odds ratio 5.3, 95% CI 4.63-6.08, P<.001) more likely to have a stimulant prescription than those without hospitalization. There were no significant associations between stimulant prescription and the total length of inpatient stay (odds ratio 1, 95% CI 1-1, P=.13).

Conclusions

The prescription of stimulant medication in Switzerland increased slightly but continuously over years, but at lower rates compared to the estimated prevalence of central hypersomnolence disorders and attention-deficit/hyperactivity disorders/attention deficit disorders. Most stimulants are prescribed by psychiatrists, closely followed by general practitioners. The increased odds for hospitalization to psychiatric institutions for stimulant receivers reflects the severity of disease and the higher psychiatric comorbidities in these patients.

Identifying time-resolved features of nocturnal sleep characteristics of narcolepsy using machine learning

The differential diagnosis of narcolepsy type 1, a rare, chronic, central disorder of hypersomnolence, is challenging due to overlapping symptoms with other hypersomnolence disorders. While recent years have seen significant growth in our understanding of nocturnal polysomnography narcolepsy type 1 features, there remains a need for improving methods to differentiate narcolepsy type 1 nighttime sleep features from those of individuals without narcolepsy type 1. We aimed to develop a machine learning framework for identifying sleep features to discriminate narcolepsy type 1 from clinical controls, narcolepsy type 2 and idiopathic hypersomnia. The population included polysomnography data from 350 drug-free individuals (114 narcolepsy type 1, 90 narcolepsy type 2, 105 idiopathic hypersomnia, and 41 clinical controls) collected at the National Reference Centers for Narcolepsy in Montpelier, France. Several sets of nocturnal sleep features were explored, as well as the value of time-resolving sleep architecture by analysing sleep per quarter-night. Several patterns of nighttime sleep evolution emerged that differed between narcolepsy type 1, clinical controls, narcolepsy type 2 and idiopathic hypersomnia, with increased nighttime instability observed in patients with narcolepsy type 1. Using machine learning models, we identified rapid eye movement sleep onset as the best single polysomnography feature to distinguish narcolepsy type 1 from controls, narcolepsy type 2 and idiopathic hypersomnia. By combining multiple feature sets capturing different aspects of sleep across quarter-night periods, we were able to further improve between-group discrimination and could identify the most discriminative sleep features. Our results highlight salient polysomnography features and the relevance of assessing their time-dependent changes during sleep that could aid diagnosis and measure the impact of novel therapeutics in future clinical trials.

Connecting clinicians and patients: The language of narcolepsy

Narcolepsy is a rare lifelong sleep disorder characterized by excessive daytime sleepiness with variable expression of cataplexy, sleep paralysis, sleep-related hallucinations and disrupted nocturnal sleep. Affected individuals also experience additional impairing symptoms, including (but not limited to) difficulties with attention, memory and concentration, brain fog, mood instability and fatigue, with a substantial impact on everyday life. Diagnostic delays of up to 10 years are common, primarily due to the substantial heterogeneity in clinical presentation of narcolepsy symptoms and presence of significant comorbidities. The disconnect in language used by clinicians and patients could be a factor contributing to diagnostic delays, but it has not been much studied. We followed a two-part approach to investigate the impact of this possible mismatch in language use. Firstly, a comprehensive literature search was conducted to identify publications reporting discrepancies in language relating to narcolepsy symptoms used by clinicians and patients. As a gap in the literature was anticipated, we supplemented the search results with practical strategies based on our clinical experience to facilitate dialog between clinicians and people living with narcolepsy, as well as proposing future research ideas. The findings of the narrative review, complemented by expert clinical opinion, are intended to help clinicians recognize narcolepsy symptoms and to refer patients with suspected narcolepsy, when appropriate. Although it is unknown to what extent a disconnect in language may contribute to diagnostic delays, we hope that better recognition of the varied clinical presentations of narcolepsy will lead to timelier diagnosis and help improve patient outcomes.

Recent insights into the pathophysiology of narcolepsy type 1

Narcolepsy type 1 (NT1) is a sleep-wake disorder in which people typically experience excessive daytime sleepiness, cataplexy and other sleep-wake disturbances impairing daily life activities. NT1 symptoms are due to hypocretin deficiency. The cause for the observed hypocretin deficiency remains unclear, even though the most likely hypothesis is that this is due to an auto-immune process. The search for autoantibodies and autoreactive T-cells has not yet produced conclusive evidence for or against the auto-immune hypothesis. Other mechanisms, such as reduced corticotrophin-releasing hormone production in the paraventricular nucleus have recently been suggested. There is no reversive treatment, and the therapeutic approach is symptomatic. Early diagnosis and appropriate NT1 treatment is essential, especially in children to prevent impaired cognitive, emotional and social development. Hypocretin receptor agonists have been designed to replace the attenuated hypocretin signalling. Pre-clinical and clinical trials have shown encouraging initial results. A better understanding of NT1 pathophysiology may contribute to faster diagnosis or treatments, which may cure or prevent it.

Evaluation of pitolisant, sodium oxybate, solriamfetol, and modafinil for the management of narcolepsy: a retrospective analysis of the FAERS database

Objective

Narcolepsy, a rare neurological disorder believed to have an autoimmune etiology, necessitates lifelong management. This study aimed to provide evidence supporting the safety of pharmacological treatment for narcolepsy.

Methods

Five-year data on pitolisant, sodium oxybate, solriamfetol, and modafinil were extracted from the FDA Adverse Event Reporting System (FAERS) self-reporting database for the period spanning from 2019 to 2023. Various statistical methods, including the reporting odds ratio (ROR), proportional reporting ratio (PRR), Bayesian confidence propagation neural network analysis (BCPNN), and multi-item gamma Poisson shrinker (MGPS), were employed to quantify the signals. Finally, a comparative analysis was conducted between demographic data, outcomes, and inherent associations among the medications and the signals.

Results

After data analysis, we obtained 50 signals (a cumulative count of 762 cases) for pitolisant, 640 signals (corresponding to 46,962 cases) for sodium oxybate, 40 signals (equivalent to 1,228 cases) for solriamfetol, and finally, 72 signals (representing 632 cases) for modafinil. The majority of these patients were female. Psychiatric and nervous system disorders were identified as the predominant adverse drug events (ADEs). For sodium oxybate, it is crucial to consider psychiatric disorders (such as suicidal ideation), respiratory disorders (including sleep apnea syndrome and respiratory depression), and signs of pregnancy and congenital familial diseases. For solriamfetol, noteworthy new ADEs include drug inefficacy, suicidal ideation, restless legs syndrome, and somnambulism. Furthermore, a relationship has been observed between modafinil use and restricted fetal growth, spontaneous abortion, cognitive disorders, and drug inefficacy and abuse.

Conclusion

The majority of observed adverse reactions in this study were consistent with those listed in the product instructions. However, potential novel or notable ADE signals were identified through real-world pharmacovigilance analysis. It is anticipated that this paper will offer additional information regarding safe and rational medication for narcolepsy.

REM sleep in narcolepsy

Narcolepsy is mainly associated with excessive daytime sleepiness, but the characteristic feature is abnormal rapid eye movement (REM) sleep phenomena. REM sleep disturbances can manifest as cataplexy (in narcolepsy type 1), sleep paralysis, sleep-related hallucinations, REM sleep behavior disorder, abnormal dreams, polysomnographic evidence of REM sleep disruption with sleep-onset REM periods, and fragmented REM sleep. Characterization of REM sleep and related symptoms facilitates the differentiation of narcolepsy from other central hypersomnolence disorders and aids in distinguishing between narcolepsy types 1 and 2. A circuit comprising regions within the brainstem, forebrain, and hypothalamus is involved in generating and regulating REM sleep, which is influenced by changes in monoamines, acetylcholine, and neuropeptides. REM sleep is associated with brainstem functions, including autonomic control, and REM sleep disturbances may be associated with increased cardiovascular risk. Medications used to treat narcolepsy (and REM-related symptoms of narcolepsy) include stimulants/wake-promoting agents, pitolisant, oxybates, and antidepressants; hypocretin agonists are a potential new class of therapeutics. The role of REM sleep disturbances in narcolepsy remains an area of active research in pathophysiology, symptom management, and treatment. This review summarizes the current understanding of the role of REM sleep and its dysfunction in narcolepsy.

Sex disparities in clinical features and burden of narcolepsy type 1

To investigate potential sex-related differences in patients with narcolepsy type 1, we carried out an analysis of baseline data from 93 women and 89 men with narcolepsy type 1 who participated in the TElemedicine for NARcolepsy (TENAR) trial. The following data were considered: sociodemographics; diagnostic (disease history, polysomnography, orexin, human leukocyte antigen) and clinical features, including sleepiness (Epworth Sleepiness Scale), cataplexy and other narcolepsy symptoms; disease severity (Narcolepsy Severity Scale); pharmacological treatment; depressive symptoms (Beck Depression Inventory); and self-reported relevance of eight narcolepsy-related issues. We found that, compared with men, significantly more women reported automatic behaviours (55.4% versus 40%) and had higher Epworth Sleepiness Scale (median 10 versus 9) and Beck Depression Inventory scores (median 10.5 versus 5), and there was a trend for a higher Narcolepsy Severity Scale total score in women (median 19 versus 18, p = 0.057). More women than men were officially recognized as having a disability (38% versus 22.5%) and considered 5/8 narcolepsy-related issues investigated as a relevant problem. More severe sleepiness and a greater narcolepsy-related burden in women could mirror sex differences present in the general population, or may be related to suboptimal management of narcolepsy type 1 or to more severe depressive symptoms in women. Future studies and guidelines should address these aspects.

Microglia Density and Its Association With Disease Duration, Severity, and Orexin Levels in Patients With Narcolepsy Type 1

BACKGROUND AND OBJECTIVES

Narcolepsy type 1 (NT1) is due to the loss of hypothalamic neurons that produce orexin (ORX), by a suspected immune-mediated process. Rare postmortem studies are available and failed to detect any inflammation in the hypothalamic region, but these brains were collected years after the first symptoms. In vivo studies close to disease onset are lacking. We aimed to explore microglia density in the hypothalamus and thalamus in NT1 compared with controls using [18F]DPA-714 PET and to study in NT1 the relationships between microglia density in the hypothalamus and in other regions of interest (ROIs) with disease duration, severity, and ORX levels.

METHODS

Patients with NT1 and controls underwent a standardized clinical evaluation and [18F]DPA-714 PET imaging using a radiolabeled ligand specific to the 18 kDa translocator protein (TSPO). TSPO genotyping determined receptor affinity. Images were processed on peripheral module interface using standard uptake value (SUV) on ROIs: hypothalamus, thalamus, frontal area, cerebellum, and the whole brain. SUV ratios (SUVr) were calculated by normalizing SUV with cerebellum uptake.

RESULTS

A total of 41 patients with NT1 (21 adults, 20 children, 10 with recent disease onset <1 year) and 35 controls were included, with no significant difference between groups for [18F]DPA-714 binding (SUV/SUVr) in the hypothalamus and thalamus. Unexpectedly, significantly lower SUVr in the whole brain was found in NT1 compared with controls (0.97 ± 0.06 vs 1.08 ± 0.22, p = 0.04). The same finding between NT1 and controls in the whole brain was observed in those with high or mixed TSPO affinity (p = 0.03 and p = 0.04). Similar trend was observed in the frontal area in NT1 (0.96 ± 0.09 vs 1.09 ± 0.25, p = 0.05). In NT1, no association was found between SUVr in different ROIs and age, disease duration, severity, or ORX levels.

DISCUSSION

We found no evidence of in vivo increased microglia density in NT1 compared with controls, even close to disease onset, and even unexpectedly a decrease in the whole brain of these patients. These findings do not support the presence of neuroinflammation in the destruction process of ORX neurons.

TRIAL REGISTRATION INFORMATION

ClinicalTrials.org NCT03754348.

Challenges in the Management of Narcolepsy in a Resource Limited Setting: A Case Report

The management of Narcolepsy, from the initial presentation to the long-term management and follow-up, remains a challenging endeavor, especially in developing climes. Worldwide, it has been recognized as a medical condition that is frequently associated with initial misdiagnoses, and delays in definitive management, further highlighted, in resource-limited settings like Nigeria where issues are further compounded by social, cultural, and political factors. In this report, we aim to shed some light on the peculiar challenges encountered by clinicians in Nigeria, and in other similar settings, in the process of diagnosis and management of narcolepsy. We present a case of a 17-year-old male teenager with Narcolepsy Type 1 (NT1) who had been previously managed as a case of Juvenile Absence Epilepsy in various centers prior to presentation at our facility. The symptoms began two years prior to presentation at our outpatient clinic, and they were excessive daytime sleepiness, cataplexy, and sleep paralysis. The symptoms were corroborated by laboratory parameters - reduced mean sleep latency (conducted in an improvised sleep laboratory), and a low cerebrospinal fluid (CSF) hypocretin level. The patient was initially placed on Modafinil for excessive daytime sleepiness and a trial of Fluoxetine for the Cataplexy. However, due to the scarcity of Modafinil, behavioral modifications - scheduled sleep naps and sleep hygiene - were eventually employed. Narcolepsy is a debilitating illness, and consequently, the far-reaching effects of these challenges must be understood. It is important that concerted efforts be made towards improving the overall quality of care received by patients from the early identification to the treatment of narcolepsy in the Nigerian healthcare system.

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.

Guardians of Rest? Investigating the gut microbiota in central hypersomnolence disorders

In recent years, there has been an increased interest in elucidating the influence of the gut microbiota on sleep physiology. The gut microbiota affects the central nervous system by modulating neuronal pathways through the neuroendocrine and immune system, the hypothalamus-pituitary-adrenal axis, and various metabolic pathways. The gut microbiota can also influence circadian rhythms. In this study, we observed the gut microbiota composition of patients suffering from narcolepsy type 1, narcolepsy type 2, and idiopathic hypersomnia. We did not observe any changes in the alpha diversity of the gut microbiota among patient groups and healthy controls. We observed changes in beta diversity in accordance with Jaccard dissimilarities between the control group and groups of patients suffering from narcolepsy type 1 and idiopathic hypersomnia. Our results indicate that both these patient groups differ from controls relative to the presence of rare bacterial taxa. However, after adjustment for various confounding factors such as BMI, age, and gender, there were no statistical differences among the groups. This indicates that the divergence in beta diversity in the narcolepsy type 1 and idiopathic hypersomnia groups did not arise due to sleep disturbances. This study implies that using metabolomics and proteomics approaches to study the role of microbiota in sleep disorders might prove beneficial.

The transcriptomics profiling of blood CD4 and CD8 T-cells in narcolepsy type I

Background

Narcolepsy Type I (NT1) is a rare, life-long sleep disorder arising as a consequence of the extensive destruction of orexin-producing hypothalamic neurons. The mechanisms involved in the destruction of orexin neurons are not yet elucidated but the association of narcolepsy with environmental triggers and genetic susceptibility (strong association with the HLA, TCRs and other immunologically-relevant loci) implicates an immuno-pathological process. Several studies in animal models and on human samples have suggested that T-cells are the main pathogenic culprits.

Methods

RNA sequencing was performed on four CD4 and CD8 T-cell subsets (naive, effector, effector memory and central memory) sorted by flow cytometry from peripheral blood mononuclear cells (PBMCs) of NT1 patients and HLA-matched healthy donors as well as (age- and sex-) matched individuals suffering from other sleep disorders (OSD). The RNAseq analysis was conducted by comparing the transcriptome of NT1 patients to that of healthy donors and other sleep disorder patients (collectively referred to as the non-narcolepsy controls) in order to identify NT1-specific genes and pathways.

Results

We determined NT1-specific differentially expressed genes, several of which are involved in tubulin arrangement found in CD4 (TBCB, CCT5, EML4, TPGS1, TPGS2) and CD8 (TTLL7) T cell subsets, which play a role in the immune synapse formation and TCR signaling. Furthermore, we identified genes (GZMB, LTB in CD4 T-cells and NLRP3, TRADD, IL6, CXCR1, FOXO3, FOXP3 in CD8 T-cells) and pathways involved in various aspects of inflammation and inflammatory response. More specifically, the inflammatory profile was identified in the "naive" subset of CD4 and CD8 T-cell.

Conclusion

We identified NT1-specific differentially expressed genes, providing a cell-type and subset specific catalog describing their functions in T-cells as well as their potential involvement in NT1. Several genes and pathways identified are involved in the formation of the immune synapse and TCR activation as well as inflammation and the inflammatory response. An inflammatory transcriptomic profile was detected in both "naive" CD4 and CD8 T-cell subsets suggesting their possible involvement in the development or progression of the narcoleptic process.

Narcolepsies, update in 2023

Narcolepsy type 1 (NT1) and type 2 (NT2), also known as narcolepsy with and without cataplexy, are sleep disorders that benefited from major scientific advances over the last two decades. NT1 is caused by the loss of hypothalamic neurons producing orexin/hypocretin, a neurotransmitter regulating sleep and wake, which can be measured in the cerebrospinal fluid (CSF). A low CSF level of hypocretin-1/orexin-A is a highly specific and sensitive biomarker, sufficient to diagnose NT1. Orexin-deficiency is responsible for the main NT1 symptoms: sleepiness, cataplexy, disrupted nocturnal sleep, sleep-related hallucinations, and sleep paralysis. In the absence of a lumbar puncture, the diagnosis is based on neurophysiological tests (nocturnal and diurnal) and the presence of the pathognomonic symptom cataplexy. In the revised version of the International Classification of sleep Disorders, 3rd edition (ICSD-3-TR), a sleep onset rapid eye movement sleep (REM) period (SOREMP) (i.e. rapid occurrence of REM sleep) during the previous polysomnography may replace the diurnal multiple sleep latency test, when clear-cut cataplexy is present. A nocturnal SOREMP is very specific but not sensitive enough, and the diagnosis of cataplexy is usually based on clinical interview. It is thus of crucial importance to define typical versus atypical cataplectic attacks, and a list of clinical features and related degrees of certainty is proposed in this paper (expert opinion). The time frame of at least three months of evolution of sleepiness to diagnose NT1 was removed in the ICSD-3-TR, when clear-cut cataplexy or orexin-deficiency are established. However, it was kept for NT2 diagnosis, a less well-characterized disorder with unknown clinical course and absence of biolo biomarkers; sleep deprivation, shift working and substances intake being major differential diagnoses. Treatment of narcolepsy is nowadays only symptomatic, but the upcoming arrival of non-peptide orexin receptor-2 agonists should be a revolution in the management of these rare sleep diseases.

Sleep Disturbances in Autoimmune Neurological Diseases

PURPOSE OF REVIEW

To summarize the current evidence on the associations between autoimmune neurological diseases (e.g., multiple sclerosis, myasthenia gravis) and sleep disturbances (e.g., insomnia, parasomnias), as well as to review the main characteristics of sleep disorders with an immune-related pathophysiology (e.g., narcolepsy, anti-IgLON5 disease).

RECENT FINDINGS

An immune-mediated damage of the areas in the central nervous system that control sleep and wake functions (e.g., hypothalamus, brainstem) can lead to sleep disorders and sleep symptoms. Sleep disturbances are the reason to seek for medical attention in certain neuroimmunological conditions (e.g., narcolepsy, anti-IgLON5 disease) where sleep-related alterations are the main clinical feature. The assessment of sleep-related symptomatology and disorders should be included in the routine evaluation of patients with autoimmune neurological diseases. Clinicians should be aware of the typical clinical presentation of certain neuroimmunological disorders mainly affecting sleep.

Pharmacological options for narcolepsy: are they the way forward?

INTRODUCTION

Narcolepsy is an under-recognized, rare neurologic disorder of hypersomnolence that is associated with increased mortality and medical and psychiatric co-morbidities. Narcolepsy exerts a substantial economic burden on patients and society. There is currently no cure, and life-long symptomatic therapy is needed. Available drugs do not modify the disease course.

AREAS COVERED

This manuscript provides an overview of narcolepsy symptoms, diagnosis, pathophysiology, current pharmacotherapies, and emerging treatments. Gaps and unresolved issues in diagnosis and management of narcolepsy are discussed to answer whether pharmacological options are the way forward.

EXPERT OPINION

Diagnostic criteria for narcolepsy (ICSD-3) need revision and greater clarity. Improved recognition of cataplexy and other symptoms through educational outreach, new biomarkers, improved test scoring through artificial intelligence algorithms, and use of machine learning may facilitate earlier diagnosis and treatment. Pharmacological options need improved symptomatic therapy in addition to targeted therapies that address the loss of hypocretin signaling. Optimal narcolepsy care also needs a better understanding of the pathophysiology, recognition of the different phenotypes in narcolepsy, identification of at-risk individuals and early recognition of symptoms, better diagnostic tools, and a database for research and disease monitoring of treatment, side-effects, and comorbidities.

Safety and efficacy of pitolisant in children aged 6 years or older with narcolepsy with or without cataplexy: a double-blind, randomised, placebo-controlled trial

BACKGROUND

Narcolepsy is a life-long disorder characterised by excessive daytime sleepiness and cataplexy, often arising in childhood or adolescence. Pitolisant, a selective histamine H3 receptor inverse agonist, has been approved in Europe and USA for adults with narcolepsy with or without cataplexy, with a favourable safety profile. This phase 3 study aimed to assess the safety and efficacy of pitolisant in children with narcolepsy with or without cataplexy.

METHODS

For this double-blind, randomised, placebo-controlled, multisite study, we recruited patients aged 6-17 years with narcolepsy with or without cataplexy in 11 sleep centres in five countries (Italy, France, Netherlands, Russia, and Finland). Participants were required to have a Pediatric Daytime Sleepiness Scale score of 15 or greater and to have not received psychostimulants for at least 14 days before enrolment; participants who needed anticataplectics (including sodium oxybate) were required to have been on a stable dose for at least 1 month. Participants were randomly assigned to treatment with pitolisant or placebo in a 2:1 ratio at the end of screening. Randomisation was stratified by study centre and treatment was allocated using an interactive web response system. After a 4-week screening period including a 2-week baseline period, patients entered in a 4-week individual up-titration scheme from 5 mg a day to a maximum of 40 mg a day of pitolisant or placebo; treatment was administered at a stable dose for 4 weeks, followed by a 1-week placebo period. For the primary analysis, we assessed pitolisant versus placebo using change in the Ullanlinna Narcolepsy Scale (UNS) total score from baseline to the end of double-blind period in the full analysis set, defined as all randomly allocated patients who received at least one dose of treatment and who had at least one baseline UNS value. A decrease in the UNS total score reflects a reduction in both excessive daytime sleepiness and cataplexy. All adverse events were assessed in the safety population, defined as all participants who took at least one dose of study medication. An open-label follow-up is ongoing. This study is registered at ClinicalTrials.gov, NCT02611687.

FINDINGS

Between June 6, 2016, and April 3, 2021, we screened 115 participants and 110 were randomly assigned (mean age 12·9 [SD 3·0] years, 61 [55%] male, and 90 [82%] with cataplexy; 72 assigned to pitolisant and 38 to placebo); 107 (70 receiving pitolisant and 37 receiving placebo) completed the double-blind period. The mean adjusted difference in UNS total score from baseline to the end of the double-blind period was -6·3 (SE 1·1) in the pitolisant group and -2·6 (1·4) in the placebo group (least squares mean difference -3·7; 95% CI -6·4 to -1·0, p=0·007). Treatment-emergent adverse events were reported in 22 (31%) of 72 patients in the pitolisant group and 13 (34%) of 38 patients in the placebo group. The most frequently reported adverse events (affecting ≥5% of patients) in either group were headache (14 [19%] in the pitolisant group and three [8%] in the placebo group) and insomnia (five [7%] in the pitolisant group and one [3%] in the placebo group).

INTERPRETATION

Pitolisant treatment resulted in an improvement in narcolepsy symptoms in children, although the UNS was not validated for use in children with narcolepsy when our study began. The safety profile was similar to that reported in adults but further studies are needed to confirm long-term safety.

FUNDING

Bioprojet.

Psychotic Episode and Schizophrenia in Slovakian Narcolepsy Database

Narcolepsy type 1 (NT1), a central disorder of hypersomnolence, is associated with mood, anxiety or hyperactivity mental disorders. Association with psychotic episode or schizophrenia is rare and could be the source of diagnostic and therapeutic difficulties. Their frequency in the national narcolepsy database has not been systematically studied. The aim of the presented study was to calculate the frequency of NT1 patients diagnosed with psychosis and/or schizophrenia, to identify clinical characteristics of these cases, and to look for narcoleptic and psychotic symptoms during re-evaluation years later. We identified three (4%) cases diagnosed with a psychotic episode in the course of NT1. They were diagnosed with NT1 by age ≤18 years. In the re-evaluation (mean follow-up 9.8 years), we identified one case with a dual diagnosis of NT1 and schizophrenia; two cases were diagnosed with a solitary psychotic episode in the course of NT1. NT1 patients diagnosed in the age ≤18 years are at higher risk of psychotic episode, and this may be related to higher vulnerability during the ongoing neurodevelopmental period. Comorbid schizophrenia with NT1 in the Slovakian Narcolepsy Database was within the prevalence expected in the general population. The solitary psychotic episode in the course of NT1 did not reduce the possibility of subsequent symptomatic treatment afterwards.

Central Disorders of Hypersomnolence: Association with Fatigue, Depression and Sleep Inertia Prevailing in Women

Fatigue, depression, and sleep inertia are frequently underdiagnosed manifestations in narcolepsy and idiopathic hypersomnia. Our cross-sectional study design included diagnostic interview accompanied by assessment instruments and aimed to explore how these factors influence disease severity as well as to elucidate any sex predisposition. One hundred and forty-eight subjects (female 63%) were divided into narcolepsy type 1 (NT1; n = 87, female = 61%), narcolepsy type 2 (NT2; n = 22, female = 59%), and idiopathic hypersomnia (IH; n = 39, female = 69%). All subjects completed a set of questionnaires: Epworth Sleepiness Scale (ESS), Hospital Anxiety and Depression Scales (HADS), Fatigue Severity Scale (FSS), and Sleep Inertia Questionnaire (SIQ). In narcoleptic subjects, questionnaire data were correlated with the Narcolepsy Severity Scale (NSS), and in subjects with idiopathic hypersomnia, with the Idiopathic Hypersomnia Severity Scale (IHSS). The highest correlation in narcoleptic subjects was found between NSS and ESS (r = 0.658; p < 0.0001), as well as FSS (r = 0.506; p < 0.0001), while in subjects with idiopathic hypersomnia, the most prominent positive correlations were found between IHSS and SIQ (r = 0.894; p < 0.0001), FSS (r = 0.812; p < 0.0001), HADS depression scale (r = 0.649; p = 0.0005), and HADS anxiety scale (r = 0.528; p < 0.0001). ESS showed an analogic correlation with disease severity (r = 0.606; p < 0.0001). HADS anxiety and depression scores were higher in females (p < 0.05 and p < 0.01), with similar results for FSS and SIQ scales (p < 0.05 for both), and a trend toward higher ESS values in females (p = 0.057). Our study illustrates that more attention should be focused on pathophysiological mechanisms and associations of fatigue, depression, as well as sleep inertia in these diseases; they influence the course of both illnesses, particularly in women.