0521 Comorbid Insomnia and Sleep Apnea: Association with Nocturnal Hypoxic Burden

Abstract Introduction The phenotype of Comorbid Insomnia and Obstructive Sleep Apnea (COMISA) represents a formidable clinical challenge, intrinsically linked to heightened cardiovascular and metabolic morbidity. Hypoxic Burden (HB), quantified as the cumulative exposure to intermittent hypoxemia. We postulate that HB acts as a persistent physiological stressor, exacerbating underlying hyperarousal and significantly contributing to Sleep Maintenance Difficulty (SMD), a hallmark complaint of insomnia. To evaluate the association between Wake After Sleep Onset (WASO), an objective polysomnographic marker of Sleep Maintenance Difficulty, and Hypoxic Burden (HB) in patients diagnosed with Obstructive Sleep Apnea (OSA). Methods This was a cross-sectional study nested within a larger cohort, evaluating 36 individuals (58.1% female; mean age 53.95 + 11.86 years). Participants with established OSA were included. Data collected encompassed: Body Mass Index (BMI), Oxygen Desaturation Index (ODI), heart rate (HR), oxygen saturation (SpO₂), time of saturation < 90% (TS < 90%), Insomnia Severity Index (ISI), and Hypoxic Burden (HB). HB was measured using a validated formula considering the area under the curve of oxyhemoglobin desaturations ≥ 3%. Results The median WASO for the sample was 43.50 (IQR 18.75 – 76.63) minutes. Notably, 68.2% of individuals exhibited a WASO of at least 30 minutes. Furthermore, WASO demonstrated correlations with several key parameters: HL (r = -0.455; p = 0.034), ODI (r = -0.378; p = 0.011), Age (r = -0.389; p = 0.073), BMI (r = -0.463; p = 0.030), minimum HR (r = 0.283; p = 0.201), mean HR (r = 0.187; p = 0.404), maximum HR (r = 0.538; p = 0.10), ΔHR (r = 0.558; p = 0.007), mean SpO₂ (r = 0.658; p = 0.003), maximum SpO₂ ( r = 0.521; p = 0.013), TS< 90% (r = - 0.597; p = 0.003), total time in hipoxemia (r = -0.127; p = 0.574), EPW (r = -0.319; p = 0.148), ISI (r = 0.294; p = 0.183). Conclusion These preliminary data demonstrate that HB is inversely associated with WASO in patients with OSA. This suggests that HB may be a key pathophysiological factor driving Sleep Maintenance Difficulty in the challenging COMISA phenotype. Support (if any)