Obstructive sleep apnea (OSA) is the most common type of sleep-related breathing disorder, characterized by repeated episodes of upper airway collapse and resulting hypoxia during sleep. Intermittent hypoxemia may exert a multisystemic impact and modulate the course of comorbidities. Pathophysiological mechanisms such as oxidative stress, inflammation, and endothelial dysfunction contribute to adverse health outcomes, including cardiovascular disease, cerebrovascular complications, metabolic disorders, cancer, neurodegenerative conditions, or behavioral abnormalities. Treatment of OSA may mitigate the progression of comorbidities and reduce the associated social and economic burden. This literature review aims to explore the relationships between OSA and selected co-morbid diseases, including COPD , stroke, diabetes, cancer and hypertension, utilizing the cohort studies in the literature.