Atrial fibrillation (AF) is the most common cardiac arrhythmia and shares many of the same risk factors as another common clinical condition, sleep apnea. The estimated prevalence of sleep apnea has increased over the past decade, and reflects a parallel increase in the most prominent risk factors of obesity and overweight.  Both obstructive and central sleep apnea have been associated with AF in multiple studies, with the risk of AF increasing 2-4-fold compared to those without sleep disordered breathing. Continuous positive airway pressure (CPAP) has been shown to reduce the rate of AF recurrence following cardioversion and radiofrequency ablation in patients with sleep apnea.  However, the mechanisms by which sleep apnea precipitates AF or vice versa, remain unclear.  In this Review, we examine the studies linking AF and sleep apnea, discuss the existing data supporting a mechanistic link between the two conditions, present the existing evidence for the effectiveness of CPAP in this growing population, and suggest possible approaches to screen AF patients for sleep disordered breathing.