 CKD patients with OSA and nocturnal hypoxemia will be randomized into one of two groups where half will receive treatment of their OSA with CPAP and the other half will not. All participants will have kidney function monitored every 3 months for a year by measurement of serum creatinine and proteinuria. The change in estimated glomerular filtration rate eGFR and proteinuria between the two groups will be assessed to determine whether treatment of OSA improves kidney function in patients with CKD. 