My Neurologist suggested a sleep study because of the fatigue. Tried CPAP for three months, first the nose hose, didn't work awful burning. Switched me to the mask no luck. Could not sleep and made it worse. Everyone I know that has gone for a sleep study needs a CPAP. Seems to be a lot of money in it for the medical suppliers. Bottom line did not work for me at all. I had abnormal deep breathing cycles, don't know if that is the same as low oxygen, I don't snore. This was before my Fibro diagnosis. Neurologist still pushing to go back to CPAP. By the way my PC said I was borderline and I was on a low setting so he agreed I was not a good candidate and the deep breathing cycles were probably affected by my meds which I was told to take the night of the sleep study. If it does not work, or makes it worse then don't use it.