A narrative review on the interplay between interstitial lung disease and obstructive sleep apnea: Mechanisms, clinical implications, and management strategies.

Interstitial lung diseases (ILDs) comprise a heterogeneous group of diffuse parenchymal lung disorders associated with progressive fibrosis, impaired gas exchange, and substantial morbidity. In recent years, the coexistence of obstructive sleep apnea (OSA) in ILD has emerged as an underrecognized yet clinically meaningful overlap. Evidence indicates that OSA is highly prevalent in ILD-even among non-obese patients-and is driven by restrictive mechanics, diminished lung volumes, impaired diaphragmatic function, and severe nocturnal hypoxemia. These physiological factors create a unique OSA phenotype that differs substantially from classic presentations observed in the general population. A growing body of data suggests that the interplay between ILD and OSA is not incidental but intertwined. Intermittent hypoxia, recurrent arousals, and autonomic activation have been proposed as mechanisms that may contribute to adverse clinical phenotypes in ILD; however, available evidence remains largely observational, and the independent causal contribution of OSA beyond ILD severity and nocturnal hypoxemia remains uncertain., REM-related oxygen instability, and marked sleep fragmentation-findings that may remain undetected by standard screening tools or home sleep apnea testing. Recognition of OSA in ILD is clinically important because PAP therapy, supplemented by oxygen when needed, may improve sleep quality, fatigue, daytime symptoms, and nocturnal oxygenation; whether this translates into slower ILD progression or improved survival remains unproven. Management requires individualized strategies that account for restrictive physiology, ventilatory instability, and the high burden of hypoxemia. This review synthesizes current evidence on the epidemiology, mechanisms, clinical implications, and management of OSA in ILD, highlighting the need for early screening, precise diagnostic evaluation, and tailored treatment approaches. Key knowledge gaps and priorities for future research are also outlined to guide the development of integrated, multidisciplinary care strategies for this complex patient population.