The sleep apnea syndrome occurs in 4% of adult men and 2% of adult women. Inflammation and hypoxia are intertwined at the molecular, cellular, and clinical levels. Sleep apnea influences heart rate variability, during sleep and during wakefulness. It is also an independent risk factor for stroke. Sleep apnea may also lead to cognitive dysfunction from the effects of chronic hypoxia and sympathetic stress associated with small-vessel disease in the brain, white matter ischemia, and lacunar strokes. This syndrome is a modifiable risk factor and therefore efforts to control this condition in patients at risk of vascular disease is a clinical endeavor that should be pursued vigorously, even though clinical research needs to persist in its quest to answer pressing pathophysiological questions. Emerging evidence suggests that restless legs syndrome (RLS) and periodic limb movements of sleep (PLMS) represent risk factors for cardio- and cerebrovascular disease, even leading to stroke.