Idiopathic hypersomnia (IH) is a chronic neurologic disorder that results in daytime sleepiness. It often involves some or all of the following:
Roughly 1.5% of the US population has idiopathic hypersomnia.2
IH is considered a disorder of neurologic origin, classified as a central disorder of hypersomnolence. It is often categorized together with other sleep disorders such as narcolepsy type 1 and type 2 (see Figure 1 below), and Kleine-Levin syndrome.1
As the term “idiopathic” implies, the exact cause of IH is presently unknown. However, there may be a genetic predisposition, with certain studies implicating reduced signaling of orexin and the homozygous PER2 gene variant.3 Triggers can include abrupt change in sleep-wake habits, overexertion, general anesthesia, viral illness, and mild head trauma.1 But generally, the precise underlying cause is unknown, making assessment and diagnosis a challenge for clinicians.
Data suggesting a 1.5% prevalence indicate that IH is more common than previously known, and may have a prevalence similar to other neurologic and psychiatric conditions that are more widely recognized.2
IH is one of multiple sleep-wake disorders that is often difficult to diagnose accurately and in a timely manner. However, through a thorough work-up and understanding of differential diagnosis, together with an expansion of management options, healthcare practitioners are more equipped than ever to personalize the care of each patient. Indeed, in the past 20 years, considerable advances have expanded our understanding of the clinical manifestations, etiology, diagnosis, and management of hypersomnia.
We invite you to explore the rest of our site on IH, in which we talk through various aspects of cardiovascular risk assessment, cognitive impact, treatment, and patient support strategies. To further your knowledge of IH, we have also provided a valuable list of additional reading and resources.
