red1 wrote:I know I do have allergies to dust & cats. Fortunately I no longer have a cat. Dust on the other hand ...
Ah.... dust! The very first thing my Sleep Specialist had me do was replace my down comforter with something non-allergenic, wipe down the walls of my bedroom, vacuum, and wash the curtains. I don't know if I am allergic to feathers, but she thought it would be a non-instrusive first step. Judging from your remark about dust, I imagine you're about as thrilled with housework as I am.

After I did all that, I had a sneezing fit to beat the band, which tells me I had a lot of allergens in my bedroom. If you didn't do a good cleaning after the cat's departure, some residual fur and dander might still be hanging around in your house. I recommend you do this cleaning overhaul early in the day so that whatever dust remains will have settled and your body has time long before before bedtime to process any allergens it took in.
I also use the NeilMed saline rinse. They say to use it at least an hour before bedtime. I use it at least 3 hours beforehand to make sure all the water is out.
Breathe-right strips can hold your nostrils open. I don't know if that is relevant for you. It is for me b/c my nose is so narrow. I do everything I can to allow air into my nose—even as a ffm-wearer.
If you feel OK about being on something like Claritin long-term, you could try that too.
My sinuses used to alternate their congestion all night long. The past couple of months, though, I noticed that it's mainly on one side. So now I sleep on my non-congested side. I don't know if you've tried that, but it might make breathing easier for you.
That's wonderful that you noticed the relationship between congestion and your AHI. Multiple interventions for possible allergies might be the key.
Good luck!