**5. Sleep Apnea Syndrome (SAS)**

Sleep apnea is classified as obstructive (OSA) due to intermittent closure of the upper airway or central due to intermittent loss of respiratory drive or both (mixed). More than 50% of patients with ESRD have sleep apnea (7, 19). Prevalence appears to be similar in advanced CKD patients who are not on dialysis and those treated with peritoneal or hemodialysis (7, 20). Sleep Disordered Breathing (SDB) is observed with similar frequency in dialysis dependent and dialysis independent CKD patients. Sleep apnea in CKD patients is more frequently obstructive (21).
