getting worn down
I go through cycles where I sleep way more than I should too. The way the human body uses sleep is quite interesting. We cycle in 30 minute increments, so if we break a pattern somewhere in the middle of that, we can really get out of sync and it takes awhile to return to normal. Of course, that's NORMAL normal, not CF normal.
Having CF compounds the problem. You could be right about the staph aureus. It's best to check with the doctor on that one, if for no other reason than to get a sputum culture so that you can compare this version of "sick" to other instances of when you don't feel well in the future. Perhaps you and your doc can detect a pattern and find a reasonable solution.
I find that when I get off track like that, it's because I've been neglecting my body in more ways than just overexerting it. I've learned that I am profoundly affected by caffeine, so I avoid that. I also do much better with my sinus problems and congestion when I stay well hydrated.
You said this is an ongoing problem--does it happen seasonally? With your menstrual cycle? Too much spring cleaning? Are you losing weight too? The problem could be any number of things. Perhaps you can try adding a little bit of salt to a bottle of water, and make sure you refill it at least 8 times during the day. It's a simplistic remedy, but the body cells need water to survive and function. Any little bit you can give your body to make its job easier is, in my opinion, a good thing.
Feel better!