Abstract
BACKGROUND: Obstructive sleep apnea (OSA) and chronic obstructive pulmonary disease (COPD) are prevalent conditions with overlapping clinical features and shared consequences on autonomic function. Heart rate variability (HRV), a non-invasive biomarker of autonomic nervous system activity, may offer diagnostic, prognostic, and therapeutic insights in this patient population. METHODS: A comprehensive literature review was conducted using PubMed, Google Scholar, and MEDLINE to identify peer-reviewed English-language studies published between January 2015 and December 2024. Studies were included if they evaluated HRV parameters in individuals with OSA, COPD, or overlap syndrome, explored HRV as a marker of disease severity or progression. A total of 239 studies were identified; after screening, 41 met the inclusion criteria. RESULTS: The analysis revealed consistent evidence linking reduced HRV with both OSA and COPD severity. HRV alterations were more pronounced in overlap syndrome, reflecting synergistic autonomic dysfunction. HRV showed potential in differentiating disease stages, predicting cardiovascular risk, and evaluating treatment efficacy, particularly for CPAP therapy in OSA. Short-term HRV was particularly sensitive to autonomic changes, while long-term recordings helped track disease progression. Emerging evidence supports the use of HRV derived from wearable technologies as a viable screening tool for health and wellness. CONCLUSION: HRV is a valuable, non-invasive tool for assessing autonomic dysfunction in OSA, COPD, and their overlap. It offers significant potential for early diagnosis, disease monitoring, and treatment evaluation. Integrating HRV into clinical practice, could enhance diagnostic efficiency, reduce healthcare burden, and improve outcomes in high-risk respiratory populations. Furthermore, longitudinal studies are warranted to standardise HRV thresholds and validate their use in routine screening protocols.