In six patients with chronic bradydysrhythmias, polysomnographies were performed before cardiac pacemaker implantation and over the week following implantation. A patient with third-degree atrioventricular block (AVB) and two patients with sinus node dysfunction (SND) were associated with sleep-disordered breathing (SDB). Their cardiac pacemaker therapies, with the increase in the average heart rate, led to a reduction of apnea-hypopnea index and/or an improvement of Cheyne-Stokes breathing. It seems that chronic bradydysrhythmia is one of the causative factors leading to SDB.