Narcolepsy as an immune-associated hypothalamic encephalopathy: orexin dysfunction and implications for precision sleep medicine.

Narcolepsy can no longer be adequately conceptualized by excessive sleepiness and cataplexy. It is increasingly recognized as a multisystem hypothalamic encephalopathy, rooted in the selective loss or dysfunction of orexin neurons, yet extending across motor, psychiatric, metabolic, and autonomic domains. Over the past two decades, convergent genetic, neuropathological, and immunological evidence has positioned narcolepsy type 1 as increasingly consistent with the spectrum of immune-mediated neurological diseases while challenging the validity of current classifications that hinge on cataplexy or multiple sleep latency testing. Borderland phenotypes, variable orexin biology, and post-infectious or secondary forms underscore the limitations of rigid categorical nosologies and support a spectrum-based framework. Advances in immunology, imaging, and systems biology highlight the limitations of purely symptomatic treatment and support the exploration of mechanism-based interventions, including orexin receptor agonism, immune-targeted strategies in early disease, and regenerative or circuit-repair approaches. In this narrative review, based on literature identified through searches of PubMed, Web of Science, and Scopus through December 2025, we synthesize evidence across epidemiology, pathophysiology, diagnosis, and therapy, and propose an integrative clinical algorithm that moves beyond categorical diagnoses toward a phenotype-biomarker-mechanism stratification model. We suggest that narcolepsy should no longer be considered a rare curiosity of sleep medicine but rather a model disorder illuminating the vulnerability of hypothalamic circuits and the complex interplay between sleep, emotion and immunity.