Different fates of excessive daytime sleepiness: survival analysis for remission

Pathophysiological Models of Hypersomnolence Associated With Depression

Up to 25% of patients with depression experience hypersomnolence (e.g., excessive daytime sleepiness, hypersomnia, and/or sleep inertia), which is associated with treatment resistance, overall poorer outcomes, and safety concerns while driving. Hypersomnolence can result from various sleep/neurological disorders or side effects from medication but is often medically unexplained in depression. In this review, we aimed to summarize the different pathophysiological models of hypersomnolence in depression to discuss their impact on nosology and to foster the development of better tailored diagnostics and treatments. We identified several potential mechanisms underlying hypersomnolence including a daytime hypoactivity of dopaminergic and noradrenergic systems, nighttime GABA (gamma-aminobutyric acid) hypoactivation, hypoperfusion, and hypoconnectivity in the medial prefrontal cortex, as well as a longer circadian period and light hyposensitivity. In some patients with depression, nighttime hyperarousal can fragment sleep and result in a complaint of excessive daytime sleepiness, thus mimicking hypersomnolence. Others might adopt maladaptive behaviors such as spending excessive time in bed, a term coined clinophilia. Objective markers of hypersomnolence, such as ambulatory ad libitum polysomnography may facilitate distinguishing between conditions that mimic hypersomnolence. Our review identified several clinical targets for hypersomnolence in depression. Low-sodium oxybate, which is approved for idiopathic hypersomnia, needs additional study in patients with depression. Neuromodulation that targets prefrontal cortex anomalies should be systematically explored, while tailored light therapy protocols may mitigate light hyposensitivity. Additionally, cognitive behavioral therapy for hypersomnolence is being developed as a nonpharmacological adjunct to these treatments.

Diagnostic challenges and burden of idiopathic hypersomnia: a systematic literature review

Idiopathic hypersomnia (IH) is a rare neurological sleep disorder, characterized by excessive daytime sleepiness despite normal sleep duration, that can significantly impact patient's lives. The burden of IH goes beyond excessive daytime sleepiness, pervading all aspects of everyday life. Characteristic and burdensome symptoms of IH include sleep inertia/drunkenness, long sleep duration, and daytime cognitive dysfunction. This systematic review assessed current knowledge regarding IH diagnostic challenges and burden of illness. Literature searches for original epidemiological, clinical, humanistic, or economic research relevant to IH published between 2012 and 2022 in MEDLINE, Embase, Cochrane, gray literature (diagnostic criteria and treatment guidelines), conferences (2019-2022), and clinical trial databases yielded 97 articles. Findings indicate that IH remains a poorly defined diagnosis of exclusion that is difficult to distinguish from narcolepsy type 2 because of symptom overlap and inadequacies of objective testing. Consequently, individuals with IH endure diagnostic delays of up to 9 years. The economic burden of IH has not been characterized to any appreciable extent. Pharmacological treatment options can improve symptoms and functional status, but rarely restores normal levels of functioning. These findings highlight the need to reclassify central disorders of hypersomnolence. Further collaboration is now required between research groups to identify and validate objective markers to help redefine diagnostic criteria for IH. This would move IH into a position that could benefit from future targeted therapeutic interventions. The study was funded by Takeda Development Center Americas, Inc.

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.

Prevalence and Course of Idiopathic Hypersomnia in the Wisconsin Sleep Cohort Study

BACKGROUND AND OBJECTIVES

Idiopathic hypersomnia (IH) is a CNS disorder of hypersomnolence of unknown etiology. Due to the requirement for objective sleep testing to diagnose the disorder, there are currently no population-based estimates of the prevalence of IH nor data regarding the longitudinal course of IH in naturalistic settings.

METHODS

Subjective and objective data from the Wisconsin Sleep Cohort study were used to identify cases with probable IH from participants with polysomnography and multiple sleep latency test data. Demographic, polysomnographic, and symptom-level data were compared between those with and without IH. Longitudinal trajectories of daytime sleepiness among those with IH were assessed to evaluate symptom persistence or remission over time.

RESULTS

From 792 cohort study participants with available polysomnography and multiple sleep latency test data, 12 cases with probable IH were identified resulting in an estimated prevalence of IH of 1.5% (95% CI 0.7-2.5, p < 0.0001). Consistent with inclusion/exclusion criteria, cases with IH had more severe sleepiness and sleep propensity, despite similar or longer sleep times. Longitudinal data (spanning 12.1 ± 4.3 years) demonstrated a chronic course of sleepiness for most of the cases with IH, though pathologic somnolence remitted in roughly 40% of cases.

DISCUSSION

These results demonstrate IH is more common in the working population than generally assumed with a prevalence on par with other common neurologic and psychiatric conditions. Further efforts to identify and diagnose those impaired by unexplained daytime somnolence may help clarify the causes of IH and the mechanisms underlying symptomatic remission.

Idiopathic hypersomnia and Kleine-Levin syndrome

Idiopathic hypersomnia (IH) and Kleine-Levin syndrome (KLS) are rare disorders of central hypersomnolence of unknown cause, affecting young people. However, increased sleep time and excessive daytime sleepiness (EDS) occur daily for years in IH, whereas they occur as relapsing/remitting episodes associated with cognitive and behavioural disturbances in KLS. Idiopathic hypersomnia is characterized by EDS, prolonged, unrefreshing sleep at night and during naps, and frequent morning sleep inertia, but rare sleep attacks, no cataplexy and sleep onset in REM periods as in narcolepsy. The diagnosis requires: (i) ruling out common causes of hypersomnolence, including mostly sleep apnea, insufficient sleep syndrome, psychiatric hypersomnia and narcolepsy; and (ii) obtaining objective EDS measures (mean latency at the multiple sleep latency test≤8min) or increased sleep time (sleep time>11h during a 18-24h bed rest). Treatment is similar to narcolepsy (except for preventive naps), including adapted work schedules, and off label use (after agreement from reference/competence centres) of modafinil, sodium oxybate, pitolisant, methylphenidate and solriamfetol. The diagnosis of KLS requires: (i) a reliable history of distinct episodes of one to several weeks; (ii) episodes contain severe hypersomnia (sleep>15h/d) associated with cognitive impairment (mental confusion and slowness, amnesia), derealisation, major apathy or disinhibited behaviour (hypersexuality, megaphagia, rudeness); and (iii) return to baseline sleep, cognition, behaviour and mood after episodes. EEG may contain slow rhythms during episodes, and rules out epilepsy. Functional brain imaging indicates hypoactivity of posterior associative cortex and hippocampus during symptomatic and asymptomatic periods. KLS attenuates with time when starting during teenage, including less frequent and less severe episodes. Adequate sleep habits, avoidance of alcohol and infections, as well as lithium and sometimes valproate (off label, after agreement from reference centres) help reducing the frequency and severity of episodes, and IV methylprednisolone helps reducing long (>30d) episode duration.

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.

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.

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.

Idiopathic Hypersomnia and Depression, the Challenge for Clinicians and Researchers

The review deals with idiopathic hypersomnia, focusing mostly on the research findings about the presence, onset and severity of excessive daytime sleepiness and depressive symptoms in patients with idiopathic hypersomnia.

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.

The Swiss Primary Hypersomnolence and Narcolepsy Cohort study (SPHYNCS): Study protocol for a prospective, multicentre cohort observational study

Narcolepsy type 1 (NT1) is a disorder with well‐established markers and a suspected autoimmune aetiology. Conversely, the narcoleptic borderland (NBL) disorders, including narcolepsy type 2, idiopathic hypersomnia, insufficient sleep syndrome and hypersomnia associated with a psychiatric disorder, lack well‐defined markers and remain controversial in terms of aetiology, diagnosis and management. The Swiss Primary Hypersomnolence and Narcolepsy Cohort Study (SPHYNCS) is a comprehensive multicentre cohort study, which will investigate the clinical picture, pathophysiology and long‐term course of NT1 and the NBL. The primary aim is to validate new and reappraise well‐known markers for the characterization of the NBL, facilitating the diagnostic process. Seven Swiss sleep centres, belonging to the Swiss Narcolepsy Network (SNaNe), joined the study and will prospectively enrol over 500 patients with recent onset of excessive daytime sleepiness (EDS), hypersomnia or a suspected central disorder of hypersomnolence (CDH) during a 3‐year recruitment phase. Healthy controls and patients with EDS due to severe sleep‐disordered breathing, improving after therapy, will represent two control groups of over 50 patients each. Clinical and electrophysiological (polysomnography, multiple sleep latency test, maintenance of wakefulness test) information, and information on psychomotor vigilance and a sustained attention to response task, actigraphy and wearable devices (long‐term monitoring), and responses to questionnaires will be collected at baseline and after 6, 12, 24 and 36 months. Potential disease markers will be searched for in blood, cerebrospinal fluid and stool. Analyses will include quantitative hypocretin measurements, proteomics/peptidomics, and immunological, genetic and microbiota studies. SPHYNCS will increase our understanding of CDH and the relationship between NT1 and the NBL. The identification of new disease markers is expected to lead to better and earlier diagnosis, better prognosis and personalized management of CDH.

Narcolepsy Type 1: A Remitting Disease? An Unusual Case Report

We describe the case of a male patient who was diagnosed with narcolepsy type 1 on the basis of sleep and wake symptoms, and the results of investigations including video-polysomnography, multiple sleep latency test, human leukocyte antigen status and orexin level in cerebrospinal fluid. During the first years after disease onset, the patient did not show any significant improvement despite treatment with a variety of stimulant and anti-cataplectic drugs. However, spontaneous remission of disease occurred after 15 years.

Potential Maladaptive Sleep-Related Cognitions in Depression with Comorbid Hypersomnolence: An Exploratory Investigation

Objective/Background: Dysfunctional sleep-related cognitions (SRCs) have been demonstrated in both insomnia and depression, but have not been evaluated in patients experiencing depression with co-occurring hypersomnolence. Given the prominence of maladaptive thinking in depression with comorbid insomnia, dysfunctional SRCs may also exist in depressed persons experiencing hypersomnolence. Identifying potentially maladaptive SRCs may assist development of cognitive-behavioral strategies to alleviate hypersomnolence and its related impairment, particularly when comorbid with depression. Participants: Twenty-two unmedicated persons with major depressive disorder (MDD) with comorbid hypersomnolence (MDD+/HYP+), as well as age- and sex-matched persons with MDD without hypersomnolence (MDD+/HYP-) and healthy controls (HC). Methods: Participants completed the Dysfunctional Beliefs and Attitudes About Sleep-16-item (DBAS-16) and underwent overnight polysomnography. Groups were compared across clinical and sleep domains, as well as DBAS-16 global, subscale, and individual item scores. Additional analyses evaluated DBAS-16 components while controlling for depression severity. Results: Groups significantly differed across all collected sleep and mood metrics consistent with diagnostic classification. MDD+/HYP+ DBAS-16 global score was significantly elevated, relative to HC, and was comparable to MDD+/HYP-. A DBAS-16 global score significant group effect was maintained while controlling for depression symptom severity, however only individual DBAS-16 items related to quantity and quality of sleep demonstrated particular relevance to MDD+/HYP+ compared to other groups. Conclusions: Results suggest potentially maladaptive SRCs in MDD+/HYP+. Further efforts are needed to clarify whether these beliefs and attitudes about sleep in persons with hypersomnolence are in fact dysfunctional, as well as identify relevant content for development of a novel hypersomnolence-related SRC metric.

Clinical neurophysiology of CNS hypersomnias

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

Measurement of symptoms in idiopathic hypersomnia

Objective

To validate the Idiopathic Hypersomnia Severity Scale (IIHSS), a self-report measure of hypersomnolence symptoms, consequences, and responsiveness to treatment.

Methods

The 14-item IHSS (developed and validated by sleep experts with patients' feedback) was filled in by 218 participants (2.3% missing data). Among the 210 participants who fully completed the IHSS, there were 57 untreated and 43 treated patients with idiopathic hypersomnia (IH) aged 16 years or older, 37 untreated patients with narcolepsy type 1 (NT1), and 73 controls without sleepiness. IHSS psychometric properties, discriminant diagnostic validity, and score changes with treatment were assessed.

Results

The IHSS showed good internal consistency and content validity. Factor analysis indicated a 2-component solution with good reliability expressed by satisfactory Cronbach α values. IHSS scores were reproducible without changes in the test–retest evaluation (13 treated and 14 untreated patients). Convergent validity analysis showed that IHSS score was correlated with daytime sleepiness, depressive symptoms, and quality of life in patients with IH. The IHSS score was lower in treated than untreated patients (5–8 unit difference, without ceiling effect). The cutoff value for discriminating between untreated and treated patients was 26/50 (sensitivity 55.8%, specificity 78.9%). IHSS scores were higher in drug-free IH patients than NT1 and controls. The best cutoff value to differentiate between untreated IH patients and controls was 22 (sensitivity 91.1%, specificity 94.5%), and 29 with NT1.

Conclusions

The IHSS is a reliable and valid clinical tool for the quantification of IH symptoms and consequences that might be useful for patient identification, follow-up, and management.

Idiopathic Hypersomnia

Idiopathic hypersomnia (IH) is a chronic neurologic disorder of daytime sleepiness, accompanied by long sleep times, unrefreshing sleep, difficulty in awakening, cognitive dysfunction, and autonomic symptoms. The cause is unknown; a genetic predisposition is suggested. Autonomic, inflammatory, or immune dysfunction has been proposed. Diagnosis involves a clinical history and objective testing. There are no approved treatments for IH, but modafinil is typically considered first-line. A substantial fraction of patients with IH are refractory or intolerant to standard treatments, and different treatment strategies using novel therapeutics are necessary. Even with current treatment options, quality of life and safety may remain impaired.