Current knowledge on the pathophysiology of idiopathic hypersomnia and potential mechanisms of action for low-sodium oxybate treatment.

STUDY OBJECTIVES

We sought to elucidate hypotheses for the pathophysiology of idiopathic hypersomnia and discuss the mechanisms by which low-sodium oxybate (LXB) improves idiopathic hypersomnia symptoms.

METHODS

Published literature on idiopathic hypersomnia sleep abnormalities, symptoms, treatments, and underlying pathophysiology was reviewed.

RESULTS

Patients with idiopathic hypersomnia often show sleep architecture alterations, such as increased sleep efficiency and reduced slow-wave sleep, although the literature lacks consensus. The current understanding of pathophysiologic changes in idiopathic hypersomnia is sparse, but several hypotheses have been posited to explain specific symptoms. Long biological sleep clock, hypofunction of default mode network, dysregulated gamma-aminobutyric acid signaling, inflammation, reduced physical activity, and immunologic abnormalities have been linked, to varying degrees, with the hallmark symptoms of idiopathic hypersomnia (excessive daytime sleepiness, sleep inertia, brain fog, dysautonomia). Treatment mechanisms may help elucidate pathophysiologic mechanisms. LXB effectively addresses idiopathic hypersomnia symptoms and is the only US-approved therapy for this indication. Oxybate, the active moiety in LXB, acts dose-dependently on gamma-aminobutyric acid and gamma-hydroxybutyrate receptors, inhibits dopamine and noradrenaline signaling, and improves sleep architecture in people with narcolepsy. The effectiveness of LXB, a sleep-inducing treatment, on idiopathic hypersomnia symptoms suggests altered sleep architecture may contribute to this disorder.

CONCLUSIONS

Idiopathic hypersomnia, a sleep disorder with potentially debilitating symptoms, remains understudied. The underlying pathophysiology of idiopathic hypersomnia needs defining; insights can be gleaned from contextualizing current knowledge about mechanisms of effective treatments, such as LXB.

CITATION

Schneider LD, Cairns A, Ruoff C, Bogan RK. Current knowledge on the pathophysiology of idiopathic hypersomnia and potential mechanisms of action for low-sodium oxybate treatment. 2025;21(7):1245-1260.

© 2025 American Academy of Sleep Medicine.