Coronary artery disease (CAD) and cerebrovascular disease (CVD) are serious conditions that have the potential to result in mortality. These disorders develop in the presence of hypertension and arteriosclerosis. Studies have demonstrated that obstructive sleep apnea (OSA) can actively contribute to the advancement of arteriosclerosis and elevate blood pressure. There is speculation that OSA may contribute to the development of coronary artery disease and cerebrovascular disease. Also, studies have shown that sleep-disordered breathing (SDB), not only OSA but also central sleep apnea (CSA), becomes more common right after acute coronary syndrome (ACS) and in the early stages after a stroke. Hence, it is crucial to take into account the timing of SDB assessments while addressing the simultaneous presence of these conditions. This chapter will first examine epidemiological research investigating the likelihood of individuals with OSA acquiring CAD and CVD. Additionally, it will analyze the progression of SDB following the occurrence of an acute phase of ACS or stroke. This study aims to look into the possible benefits of continuous positive airway pressure (CPAP) therapy in lowering the risk of developing CAD or CVD in people who have been diagnosed with OSA. Furthermore, it will underscore the significance of treating OSA following the occurrence of these illnesses. Lastly, it will investigate the potential mechanisms that explain the connection between OSA and these diseases.