Sleep apnea
I can't add to much more than what Tammy and Kathy have already said.
While undergoing all the testing to get approved for the RNY I was diagnosed with Sleep Apnea, it wasn't severe but was well on its way to become a serious problem which I was completly unaware of till that moment.
Once I was diagnosed, took about a month for the doctor to get me a mask, set me up witht he correct setting and clear me for surgery. Sleep apnea won't prevent the surgery but they have to be aware of the condition and you MUST take your CPAP machine to the hospital and use it once you are in your room! If your apnea is severe you may wake up with the CPAP machine already on, thankfully I didn't but did have to use it once I was in my own room, that first night.
Since surgery I have to contact my pulmonologist to have the techie guy come out to "recalibrate" the machine. The setting it is on is wicked high for me now, it wakes me up, dries my mouth and nose out and I can't use it .... so definitly the RNY has helped my apnea!