Fellow UARS survivor here. Some notes:

* My symptoms at the nadir were (all resolved with self-administered xPAP): chronic fatigue; chronic pain (skeletal muscles were all like bricks); insomnia throughout the night every night; tinnitus; reflux; chronic anxiety; all sorts of cognitive problems with memory, concentration and executive function.

* You describe CPAP rejection as something specific to UARS. It really is not, many people with "plain OSA" reject CPAP. For some people SDB causes intense anxiety, others get a bit numb. I guess CPAP is doable for the numb population. Obviously having resistance imposed on your breathing while being in Fight or Flight mode constantly is a big no-no. I experienced this myself, CPAP gave me back to back anxiety attacks. Describe this to doctors, and they will gaslight you. Their talk is cheap, they don't have to sleep like that. Fortunately my first device was a BiPAP (by total coincidence) and turning the BiPAP mode on was like turning a key and opening a door. I went to sleep instantly and we became best friends :) Barry Krakow MD is a rare exception. He says the following in his article [0]

> From our perspective, reliance on CPAP in a sizeable proportion of OSA/UARS patients violates the dictum, primum non nocere. Accordingly, 15 years ago we ceased use of CPAP and switched all patients to bilevel modes.

* Joseph Borelli MD, an adult UARS survivor describes his experiences in a video from the American Sleep Apnea Association. [1]

* In my experience nasal congestion can also be caused by the SDB. The Bilevel breathing assistance compensated for my nasal resistance at the beginning, and after a while my nose just opened up. I haven't had any trouble with it since, also while performing strenuous activity and sports. I never had anything done to my nose, let alone surgery.

* It's very hard to know when you are fully treated, with any intervention if there is no hard data. I started with BiPAP, and for 3 years I was adjusting my pressure every 3-4 months and gained improvement. But I was never sure that I had reached the ceiling. I did have some regular "worse days" that could be blamed on residual breathing issues. The DSX900 AutoSV records every individual breath on its SD card, so I can verify that it is achieving total flow normalization. [3]

* Around october 2020 I had some discussions, giving input to the author of this article [2] and I became sure that I had to try ASV at some point to try and achieve complete "flow normalization" which Barry Krakow MD describes in a webinar [3]. Finally I in january 2021 I had the opportunity to try a DSX900 AutoSV and copy my Bilevel settings onto it with some headroom for the ASV algorithm to work. It did turn out that I had a lot to gain cognitively, my concentration, memory and executive function became much better, particularly reading and studying "hard" text became much easier and "transparent," i.e. no more clinging to the lines of text. So this is a warning, while any relief from the most dire symptoms is good, I consider years lived with inadequate treatment to be years wasted in a sense. Of couse the 15 years I went completely untreated as a young teen going through school and university as a tired, neurotic wreck I will never get back.

* Mouth taping probably works because it keeps the lower jaw stabilized. It tends to drop and then fall back. A soft cervical collar would probably also work. My current mask (F30i) hooks under my lower lip and that probably also helps.

* I use an ultrafine allergy filter in my machine and it still does a lot of work for me, so allergies cannot be considered the main cause. In my case it's facial anatomy such as retrognathia, large tongue, Mallampati class IV.

* I was gaslighted by doctors for 3 years. I was finally diagnosed with UARS (3rd PSG with Pes this time) in october 2020 but no treatment was offered as "there was no protocol." I had to do everything myself.

* Toughing it out isn't sustainable, my final crash was in 2017.

[0] https://www.thelancet.com/journals/eclinm/article/PIIS2589-5...

[1] https://www.youtube.com/watch?v=zbdMY_qd7-s

[2] https://web.archive.org/web/20211006015015/https://sleepbrea...

[3] https://www.youtube.com/watch?t=1321&v=Syv7YcHbTCI