Review: Idiopathic Hypersomnia Carries Considerable Burden and Remains Poorly Defined

More collaboration and research efforts are needed to address the needs patients with idiopathic hypersomnia (IH). For too long, this population has experienced lacking and insufficient pharmacological treatment options, diagnostic difficulties, and excessive daily burden brought about by this condition. These conclusions were brought forth from a systematic review recently published in Sleep Research Society.¹

“Idiopathic hypersomnia (IH) is widely considered to be a rare disease characterized by excessive daytime sleepiness, including difficulty waking up and reduced focus/alertness and mental fatigue, with important consequences for those affected,” the present authors began as they highlighted the need for a more comprehensive assessment of IH-related burden. Previous studies have reported that IH can have a drastic impact on daily functioning, get in the way of social activities, affect concentration, mental health, the ability to maintain relationships, and more, with patient responses indicating that many are not satisfied with the management of their condition.^{2, 3}

Idiopathic hypersomnia belongs to a group referred to as the central disorders of hypersomnolence, which are classified by excessive daytime sleepiness | image credit: pathdoc - stock.adobe.com

IH, the current authors continued, belongs to a group referred to as the central disorders of hypersomnolence (CDHs), which are classified by excessive daytime sleepiness (EDS) and include narcolepsy types 1 and 2 (NT1 and NT2), insufficient sleep syndrome, Kleine-Levin syndrome, as well as any hypersomnia related to medication, substance use, or psychiatric/medical disorders.¹ Among this class of disorders, IH is accompanied by its own diagnostic challenges due to its resemblance to NT2, making it sometimes difficult to define the condition.

While individual components of IH-related burden have been investigated separately, the collective burden brought about by this disorder remains understudied. As such, the researchers conducted a systematic review on more recent literature on IH to develop a more comprehensive understanding of the challenges of this condition, both in diagnosis and symptom management. Databases from ClinicalTrials.gov, MEDLINE, the World Health Organization’s International Clinical Trials Registry Platform, Embase, and abstracts from the World Sleep Congress 2019 were used to identify relevant sources published within the last 10 years.

A total of 97 studies were featured in this analysis, of which 88 were original research investigations, 6 were meta-analysis or systematic literature reviews, and 3 were guidelines. No economic publications appeared in the last 10 years that reported on the financial burden—direct or societal costs related, or utilization of resources—related to IH.

The most common diagnostic criteria in their review came from the 2014 International Classification of Sleep Disorders Third Edition (ICSD-3), which determines IH based on the presence of an EDS that cannot be attributed to medication or another disorder, sleep-onset rapid eye movement periods (SOREMPs) that are limited to 0 or 1, and a Multiple Sleep LatencyTest (MSLT) that falls at or below 8 minutes. Additionally, IH can be diagnosed if an individual sleeps 11 hours or more over a 24-hour period. However, this diagnosis stills has obstacles because criteria “do not provide levels or grades of certainty for evidence supporting CDH diagnoses, adequately grade the severity of sleep-related symptoms, or state how to reliably measure and assess sleep deprivation and circadian rhythm disturbances when ruling them out in the process of diagnosing IH,” the authors wrote.

An analysis on the burden of IH revealed that many affected individuals have difficulty keeping their attention for over 1 hour, compared with the 4-hour average observed in controls. IH also contributes to a chronic, reported state of fogginess, drowsiness, or a lack of alertness. In this same vein, 1 study from their review indicated that those with IH have slower reaction times, while others revealed that patients do not feel refreshed by sleep and these symptomatic burdens vary considerably throughout this patient population.

Furthermore, a plethora of comorbidities are disproportionately linked to IH, including allergies, autoimmunity, inflammation, mental health and attention deficit complications, weight management issues, and more. For example, up to 36% of individuals with IH experience depression compared with 5% of healthy individuals. Additionally, the literature on quality of life demonstrated that IH drastically impacts individual perceptions and experiences day-to-day.

The culmination of this review provides “strong evidence that IH is a poorly defined diagnosis of exclusion and its burden extends beyond excessive sleepiness,” the authors concluded.

References

1. Boulanger T, Pigeon P, Crawford S. Diagnostic challenges and burden of idiopathic hypersomnia: a systematic literature review. Sleep Adv. 2024;5(1):zpae059. doi:10.1093/sleepadvances/zpae059

2. Stevens J, Schneider LD, Husain AM, et al. Impairment in functioning and quality of life in patients with idiopathic hypersomnia: the real world idiopathic hypersomnia outcomes study (ARISE). Nat Sci Sleep. 2023;15:593-606. doi:10.2147/NSS.S396641

3. Whalen M, Roy B, Steininger T, Dronamraju N, Enson D. 0392 patient perspective on idiopathic hypersomnia: impact on quality of life and satisfaction with the diagnostic process and management. Sleep. 2022;45:175-176. doi:10.1093/sleep/zsac079.389