Brain fog AFTER septoplasty?

Just wanted to see if anyone else has had this happen to them. To preface: I have chronis sinusitis that mostly presents itself as postnasal drip with some clogging of the nostrils as well.

I had a septoplasty almost 3 years ago to fix a deviated septum. The surgery happened in November. A few days after the surgery i started experiencing an intense brain fog for most of the day. This lasted until the Summer. Long story short, I have experienced this brain fog on and off(mostly on during the winter and off during the warmer months but not always) ever since. The brain fog typically kicks in later in the day, with me being fine for most of the morning. I feel like it’s relative to how long I sleep/what time i wake up but it’s hard to say.

The thought amongst my ENT and neurologist is that it could be my allergies/sinusitis causing me to have a sleep issue. I had a sleep study done this week and i’m waiting for the results but the technician conducting my study said that it didn’t look like I had any issues to them.

Has anyone else had this or something similar happen? Could it just be that my nose is breathing in more allergens and maybe that’s the cause? I’m lost here and it’s seriously having an effect on my quality of life.