Disorders of Excessive Daytime Sleepiness Including Narcolepsy and Idiopathic Hypersomnia

Long sleep time and excessive need for sleep: State of the art and perspectives

The mechanisms underlying the individual need for sleep are unclear. Sleep duration is indeed influenced by multiple factors, such as genetic background, circadian and homeostatic processes, environmental factors, and sometimes transient disturbances such as infections. In some cases, the need for sleep dramatically and chronically increases, inducing a daily-life disability. This "excessive need for sleep" (ENS) was recently proposed and defined in a European Position Paper as a dimension of the hypersomnolence spectrum, "hypersomnia" being the objectified complaint of ENS. The most severe form of ENS has been described in Idiopathic Hypersomnia, a rare neurological disorder, but this disabling symptom can be also found in other hypersomnolence conditions. Because ENS has been defined recently, it remains a symptom poorly investigated and understood. However, protocols of long-term polysomnography recordings have been reported by expert centers in the last decades and open the way to a better understanding of ENS through a neurophysiological approach. In this narrative review, we will 1) present data related to the physiological and pathological variability of sleep duration and their mechanisms, 2) describe the published long-term polysomnography recording protocols, and 3) describe current neurophysiological tools to study sleep microstructure and discuss perspectives for a better understanding of ENS.

Understanding and approaching excessive daytime sleepiness

Excessive daytime sleepiness (EDS) is a public health issue. However, it remains largely undervalued, scarcely diagnosed, and poorly supported. Variations in the definition of EDS and limitations in clinical assessment lead to difficulties in its epidemiological study, but the relevance of this symptom from a socioeconomic perspective is inarguable. EDS might be a consequence of several behavioural issues leading to insufficient or disrupted sleep, as well as a consequence of sleep disorders including sleep apnoea syndrome, circadian disorders, central hypersomnolence disorders (narcolepsy and idiopathic hypersomnia), other medical or psychiatric conditions, or medications. Furthermore, EDS can have implications for health as it is thought to act as a risk factor for other conditions, such as cardiovascular and neurodegenerative disorders. Because of the heterogeneous causes of EDS and the complexity of its pathophysiology, management will largely depend on the cause, with the final aim of making treatment specific to the individual using precision medicine and personalised medicine.

Diagnosis and management of sleep disorders in Prader-Willi syndrome

Clinical experience and a growing body of evidence suggest that sleep disturbances are common in people with Prader-Willi syndrome (PWS). PWS is a rare neuroendocrine disorder characterized by early hypotonia and feeding difficulties; developmental delays; endocrinopathies; and behavioral concerns, especially rigidity, anxiety, and behavioral outbursts. PWS is also characterized by decreased resting energy expenditure and transition to hyperphagia and obesity. We propose that, for many people with PWS, clinical diagnosis and management of sleep disorders is an unmet need. We present current information to suggest disordered sleep is a significant burden for individuals with PWS and often overlooked. While central and obstructive sleep apnea are more widely recognized in PWS, other sleep disorders have increasingly gained recognition, including hypersomnia, narcolepsy-like phenotypes, and insomnia. Sleep disorders can impact behavior, cognition, and quality of life and health for individuals with PWS. Our goal is to bring sleep disorders to the forefront of therapeutic intervention for patients with PWS. This paper presents a review of the literature and recommendations for clinical practice based on published research and our clinical experience as sleep specialists, geneticists, psychiatrists, pediatricians, otolaryngologists, and pulmonologists with extensive experience with this patient population. We recommend that management of sleep be considered an integral part of successful medical management of PWS. Further research concerning sleep problems in PWS is urgently needed to develop best practices and work toward a consensus statement for medical management to meet the needs of people with PWS.

CITATION

Duis J, Pullen LC, Picone M, et al. Diagnosis and management of sleep disorders in Prader-Willi syndrome. J Clin Sleep Med. 2022;18(6):1687-1696.

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.

Prevalence and factors associated with excessive and severe daytime sleepiness among healthcare university students in the Brazilian Midwest

The present study aimed to determine the prevalence of, and factors associated with excessive and severe daytime sleepiness in healthcare university students. A cross-sectional university-based study was conducted with 1,779 students from a university located in the Brazilian Midwest State of Goiás, Brazil, in 2018. Daytime sleepiness was assessed using the Epworth Sleepiness Scale (ESS) and classified as excessive daytime sleepiness (EDS; cut-off ESS score ≥10) and severe EDS (S-EDS; cut-off ESS score ≥16). Associated factors included sociodemographic, behavioural, academic, nutritional status, and sleep-related and perceived health characteristics. Poisson regression was used for the data analysis. The mean (SD) age of the sample was 22.5 (3.84) years. The prevalence of EDS was 54.4% (95% confidence interval [CI] 51.9-56.1) and S-EDS was 10.0% (95% CI 9.2-11.7). After adjustment, a higher probability of occurrence of EDS was found among women (prevalence ratio [PR] 1.37, 95% CI 1.24-1.53), younger students (PR 1.23, 95% CI 1.07-1.42), those who were studying medicine (PR 1.14, 95% CI 1.02-1.28), with poor sleep quality (PR 1.29, 95% CI 1.17-1.43), and among those who reported constant loss of sleep due to internet use (PR 1.14, 95% CI 1.02-1.27). After adjustment, the highest probability of occurrence of S-EDS was found among women (PR 1.72, 95% CI 1.22-2.43), among those with poor sleep quality (PR 2.17, 95% CI 1.54-3.08), and medical students (PR 1.39, 95% CI 1.01-1.90). In conclusion, there was a high prevalence of daytime sleepiness among healthcare university students, especially among medical students and women.

MicroRNA: A Key Player for the Interplay of Circadian Rhythm Abnormalities, Sleep Disorders and Neurodegenerative Diseases

Circadian rhythms are endogenous 24-h oscillators that regulate the sleep/wake cycles and the timing of biological systems to optimize physiology and behavior for the environmental day/night cycles. The systems are basically generated by transcription-translation feedback loops combined with post-transcriptional and post-translational modification. Recently, evidence is emerging that additional non-coding RNA-based mechanisms are also required to maintain proper clock function. MicroRNA is an especially important factor that plays critical roles in regulating circadian rhythm as well as many other physiological functions. Circadian misalignment not only disturbs the sleep/wake cycle and rhythmic physiological activity but also contributes to the development of various diseases, such as sleep disorders and neurodegenerative diseases. The patient with neurodegenerative diseases often experiences profound disruptions in their circadian rhythms and/or sleep/wake cycles. In addition, a growing body of recent evidence implicates sleep disorders as an early symptom of neurodegenerative diseases, and also suggests that abnormalities in the circadian system lead to the onset and expression of neurodegenerative diseases. The genetic mutations which cause the pathogenesis of familial neurodegenerative diseases have been well studied; however, with the exception of Huntington's disease, the majority of neurodegenerative diseases are sporadic. Interestingly, the dysfunction of microRNA is increasingly recognized as a cause of sporadic neurodegenerative diseases through the deregulated genes related to the pathogenesis of neurodegenerative disease, some of which are the causative genes of familial neurodegenerative diseases. Here we review the interplay of circadian rhythm disruption, sleep disorders and neurodegenerative disease, and its relation to microRNA, a key regulator of cellular processes.

Identifying subtypes of Hypersomnolence Disorder: a clustering analysis

BACKGROUND

Patient heterogeneity is problematic for the accurate assessment and effective treatment of Hypersomnolence Disorder. Clustering analysis is a preferred approach for establishing homogenous subclassifications. Thus, this investigation aimed to identify more homogeneous subclassifications of Hypersomnolence Disorder through clustering analysis.

METHODS

Patients undergoing polysomnography (PSG) and multiple sleep latency test (MSLT) assessment for hypersomnolence were recruited as part of a larger investigation. A sample of patients with Hypersomnolence Disorder was determined based on a post hoc chart review protocol. After removing persons with missing data, 62 participants were included in the analyses. Self-report total sleep time, Epworth Sleepiness Scale (ESS) score, and Sleep Inertia Questionnaire (SIQ) score were chosen as clustering variables to mirror Hypersomnolence Disorder diagnostic traits. A statistically-driven clustering process produced two clusters using Ward's D hierarchical approach. Clusters were compared across characteristics, self-report measures, PSG/MSLT results, and additional objective measures.

RESULTS

The resulting clusters differed across a variety of hypersomnolence-related subjective metrics and objective measurements. A more severe hypersomnolence phenotype was identified in a cluster that also had elevated depressive symptoms. This cluster endorsed significantly greater daytime sleepiness, sleep inertia, and functional impairment, while displaying longer sleep duration and worse vigilance.

CONCLUSIONS

These results provide growing support for a nosological reformulation of hypersomnolence associated with psychiatric disorders. Future research is necessary to solidify the conceptualization and characterization of unexplained hypersomnolence presenting with-and-without psychiatric illness.

Factors Associated with Excessive Daytime Sleepiness in Medical Students of a Higher Education Institution of Bucaramanga

INTRODUCTION

Excessive daytime sleepiness (EDS) can interfere with academic and professional performance, as affected individuals tend to fall asleep in situations that demand a high level of alertness. Medical students are often a population at risk of suffering from EDS due to the demanding number of study hours, the significant number of credits per subject in the academic curriculum, practical teaching sessions and hospital night shifts, which can lead to sleep deprivation or sleep debt. It is for these reasons that it is important to estimate the prevalence of EDS and its associated factors in medical students of a Higher Education Institution (HEI) in Bucaramanga, in order to implement early prevention strategies to reduce the occurrence of this problem and to improve the students' quality of life and academic performance.

MATERIAL AND METHODS

An observational, cross-sectional analytical study with a population sample of 458 medical students enrolled in the second semester of 2015 at the Universidad Autonoma de Bucaramanga (UNAB), who completed four questionnaires: Sociodemographic Variables, Epworth Sleepiness Scale, Pittsburgh Sleep Quality Index and Sleep Hygiene Index (SHI). A bivariate and multivariate analysis was performed to identify any correlations with EDS.

RESULTS

Mean student age was 20.3 years and 62.88% of the 458 respondents were women. We were able to establish that 80.75% of participants suffered from EDS and 80.55% had a negative perception of their sleep quality (OR=1.91; 95% CI, 1.11-3.29; p =0.019]. In the multivariate analysis, it was found that the risk of EDS is lower in the clinical sciences than in the basic cycle. Furthermore, it was noted that a score higher than 15 in the Sleep Hygiene Index significantly increases the risk of suffering from EDS.

CONCLUSIONS

Although EDS is very common in medical students, only a small percentage present the most severe form of this sleep disorder. Being enrolled in basic cycle subjects is associated with a higher risk of suffering EDS, so it is important for the curriculum committees of higher education institutions to regularly evaluate the number of hours of supervised and independent work performed by medical students. Finally, it is important to implement campaigns aimed at improving university students' perception of the risk of taking energy drinks and to establish sleep hygiene recommendations from the start of the academic programme.

Clinical update on central hypersomnias

The central hypersomnias encompass a range of conditions causing persisting or intermittent excessive daytime sleepiness (EDS). These conditions therefore present not infrequently in general clinical sleep practice, and remain in the differential for patients presenting with sleepiness. Our understanding of the pathophysiology, diagnosis and management of these conditions has progressed significantly over recent years, and in this article we review this group of disorders, focussing in particular on recent changes in classification and diagnosis, pathophysiological advances, and novel treatment options.