Association Between Depressive Symptoms and Altered Heart Rate Variability in Obstructive Sleep Apnea

<b>Background/Objectives:</b> Obstructive sleep apnea (OSA) is strongly associated with cardiovascular morbidity, and depressive symptoms are common in affected individuals. Both OSA and depression have been linked to autonomic dysfunction, but the independent contribution of depressive symptoms to autonomic dysfunction in OSA remains unclear. We investigated whether depressive symptom severity is associated with autonomic function, indexed by heart-rate variability (HRV), in patients with OSA. <b>Methods:</b> We retrospectively analyzed 1713 adults with OSA at a university-affiliated sleep center from 2011 to 2024. HRV was derived from electrocardiography during polysomnography, and frequency-domain indices (natural log-transformed LF, HF, VLF, TP, and LF/HF) were computed. Depressive symptoms were assessed using the Beck Depression Inventory-II (BDI-II). Associations between BDI-II and HRV indices were evaluated using univariable and multivariable linear regressions. <b>Results:</b> In univariable regression analyses, higher BDI-II scores were significantly associated with lower HRV indices (ln LF, ln HF, ln VLF, ln TP; all <i>p</i> < 0.01). In multivariable analyses, higher BDI-II scores were independently associated with lower ln LF, ln HF, and ln TP (all <i>p</i> < 0.05), adjusting for age, sex, body mass index, hypertension, diabetes, apnea-hypopnea index, arousal index, and sleep quality. <b>Conclusions:</b> Greater depressive symptom burden is independently associated with reductions in multiple HRV indices, suggesting attenuated parasympathetic activity and autonomic dysregulation in patients with OSA. These findings support integrated management strategies that address both physiological and psychological domains in OSA and motivate longitudinal studies to test whether effective depression treatment improves HRV and mitigates long-term cardiovascular risk.