Normal sleep provides a period of physiologically reduced workload for the cardiovascular system for almost one third of the human life span. Snoring, the most common disorder of sleep, heralds the presence of an unstable upper airway and alerts perceptive clinicians to the possibility of OSA. Epidemiologic evidence has implicated snoring as an independent risk factor for the development of hypertension, ischemic heart disease, and cerebral infarction. However, many investigators would attribute these adverse cardiovascular effects to the substantial prevalence of OSA in habitual snorers. The detrimental effects of OSA on hemodynamics and cardiac rhythm have been well documented, and recent data have linked OSA with increased cardiovascular mortality. Worsening hypoxemia during sleep likely contributes to the nocturnal mortality observed in patients with severe COPD. Effective treatment to prevent nocturnal hypoxemia is available for OSA and COPD, with current evidence supporting beneficial effects on survival.