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

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.

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.

Narcolepsy and rapid eye movement sleep

Since the first description of narcolepsy at the end of the 19th Century, great progress has been made. The disease is nowadays distinguished as narcolepsy type 1 and type 2. In the 1960s, the discovery of rapid eye movement sleep at sleep onset led to improved understanding of core sleep-related disease symptoms of the disease (excessive daytime sleepiness with early occurrence of rapid eye movement sleep, sleep-related hallucinations, sleep paralysis, rapid eye movement parasomnia), as possible dysregulation of rapid eye movement sleep, and cataplexy resembling an intrusion of rapid eye movement atonia during wake. The relevance of non-sleep-related symptoms, such as obesity, precocious puberty, psychiatric and cardiovascular morbidities, has subsequently been recognized. The diagnostic tools have been improved, but sleep-onset rapid eye movement periods on polysomnography and Multiple Sleep Latency Test remain key criteria. The pathogenic mechanisms of narcolepsy type 1 have been partly elucidated after the discovery of strong HLA class II association and orexin/hypocretin deficiency, a neurotransmitter that is involved in altered rapid eye movement sleep regulation. Conversely, the causes of narcolepsy type 2, where cataplexy and orexin deficiency are absent, remain unknown. Symptomatic medications to treat patients with narcolepsy have been developed, and management has been codified with guidelines, until the recent promising orexin-receptor agonists. The present review retraces the steps of the research on narcolepsy that linked the features of the disease with rapid eye movement sleep abnormality, and those that do not appear associated with rapid eye movement sleep.

A continuous approach to explain insomnia and subjective-objective sleep discrepancy

Understanding insomnia is crucial for improving its diagnosis and treatment. However, many subjective complaints about insomnia do not align with objective measures of sleep quality, as is the case in subjective-objective sleep discrepancy (SOSD). We address this discrepancy by measuring sleep intrusions and instability in polysomnographic recordings from a large clinical database. Using machine learning, we develop personalized models to infer hypnodensities-a continuous and probabilistic measure of sleep dynamics-, and analyze them via information theory to measure intrusions and instability in a principled way. We find that insomnia with SOSD involves sleep intrusions during intra-sleep wakefulness, while insomnia without SOSD shows wake intrusions during sleep, indicating distinct etiologies. By mapping these metrics to standard sleep features, we provide a continuous and interpretable framework for measuring sleep quality. This approach integrates and values subjective insomnia complaints with physiological data for a more accurate view of sleep quality and its disorders.