Sleep apnea syndrome involves recurring episodes of apnea and hypopnea during sleep and presents in two primary forms. Central sleep apnea is caused by a defect in brain signaling, while obstructive sleep apnea stems from muscle relaxation that allows soft tissue to block airflow. Both forms lead to intermittent hypoxemia and disrupted sleep architecture, with consequences that extend well beyond nighttime symptoms.
The condition causes repeated episodes of hypoxemia, reducing oxygen delivery to tissues and triggering systemic stress responses. Obstructive sleep apnea increases cardiovascular disease risk through multiple pathways, including sympathetic nervous system activation, oxidative stress, inflammation, and direct cardiac strain. Over time, these processes can lead to arrhythmias, left ventricular hypertrophy, and other cardiac complications.
A comprehensive review documented the wide-ranging associations of obstructive sleep apnea with serious health outcomes, including elevated risk of stroke (OR 3.8), mortality in severe OSA (hazard ratio 3.8), hypertension (OR 2.9), motor vehicle accidents (RR 2.4), heart failure (RR 2.4), occupational accidents (RR 2.2), and type 2 diabetes (OR 1.6). These findings underscore the systemic burden of untreated sleep apnea across multiple organ systems.
Sleep apnea frequently coexists with other respiratory conditions, termed overlap syndromes, including COPD, asthma, and interstitial lung disease. The combination of these conditions typically produces more severe hypoxemia and greater functional limitation than either condition alone. Chronic, untreated sleep apnea can also lead to pulmonary hypertension, as deventilated lung areas trigger capillary constriction and progressively elevate pulmonary arterial pressure.
Untreated sleep apnea carries serious long-term cardiovascular and pulmonary consequences. Early identification and treatment — through positive airway pressure therapy, positional interventions, or other modalities — is essential not only for symptom relief but for reducing the downstream risks of cardiovascular disease, metabolic dysfunction, and impaired perioperative safety for patients requiring surgery.