Atrial Fibrillation (A-Fib) is the most common dangerous cardiac arrhythmia. Cardiac arrhythmias are electrical disturbances in the heart muscle that affect the heart’s ability to effectively perform its primary function- pumping blood. When A-Fib is untreated or poorly treated, complications can include strokes, blindness and death. At least 75% of patients with A-Fib also suffer from sleep apnea, although ironically most are not even identified. This article demonstrates that when patients with A-Fib are treated for sleep apnea, they experience a significant reduction in the recurrence of A-Fib episodes. In addition, the primary treatment of A-Fib (ablation, medications) is more successful when sleep apnea is also treated.