I personally think that allergic reactions can be quite a contributing factors on some individials' CH's. I have some form of "Indoor Air Sickness" and if there's mold or some nasty chemicals in living quarters, it ramps up my CH activity. It has been quite difficult to connect the dots at times and keeping a diary helps me. Sneezing can help me and even prevent. I also see oxygen use as "flushing the lungs" if you are breathing air that's bad for you. Just my experience.
Thanks for contributing and I hope you meet a fellow CH'r "in the flesh" soon