This is an interesting line of research and it is the kind of well-being areas that interests most about the health sciences, specially since it intersects with the occult. I read some of the other sections of the Streamline Minds, interesting stuff. The Black Breath also seems useful and I couldn't help but think how it would be used as part of the work of the OSA, since it seems to focus on building healthy "complexes" by using suggestions, or, affirmations accompanied by breath.

For me I did feel an increase in mental clarity and also on getting juices flowing. It felt like a stretch for my brain, or as you say, a squeeze which brought a bright sensation.

Something that I found interesting was on the energetic level, which for some reason seems to be closely related to the mucous membranes (When I do magic for example, I usually feel inflammation coming down in my sinuses and ears). As much as I felt a squeeze on my brain, I felt energy activity on my head as well, probably because of the increased blood flow.