Obstructive sleep disordered breathing is more prevalent in end stage kidney disease patients than in the general population, and may participate to the increased cardiovascular mortality observed in this group of patients. Despite a significant increase in knowledge about the harmful effects of obstructive sleep apnea, the pathophysiological mechanisms are poorly understood. Recent observations suggest a causative relationship between overnight fluid displacement from the legs to the neck soft and the severity of obstructive sleep apnea. This mechanism was demonstrated in otherwise healthy subjects, in heart failure patients, and in patients with venous insufficiency. We thus suspect that this pathophysiologic mechanism could explain the increased prevalence of obstructive sleep apnea in patients with fluid overload, including chronic renal failure.