I don't think sleep apnea is a GCA problem or a PMR problem.

That being said, I developed sleep apnea after being diagnosed with PMR, I had frequent urination at night which was a clue for my primary care doctor to get a sleep study done.
https://www.sleepapnea.org/sleep-health/nighttime-urination-and-sleep-apnea/#:~:text=While%20research%20studies%20have%20established,OSA%20may%20cause%20the%20issue.
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When I did the sleep study, I was diagnosed with obstructive sleep apnea. The cause was said to be excess weight in the area of my face and neck area likely caused by prednisone
https://www.sleeptest.com/blog/post/drugs-that-can-lead-to-obstructive-sleep-apnea
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I have been off Prednisone for 3 years. People say my face looks like I have lost weight. I still need to lose more weight. My sleep apnea like so many other problems I had when I was on Prednisone has improved.
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I hated my CPAP machine at first but after I started using it all the time, I didn't need to get up every hour at night to pee.

This illustrates how one problem leads to another and another and another.. Interestingly, many of my problems are improving now that I'm not longer taking Prednisone.