What happens to you when you hold your breath after a deep full/semi-full inhalation? .. When I hold my breath after a full, or almost full inhalation and observe the effects it has on my body-mind, and go along with that feeling, things get psychedelic fast: inner high pitched noise increasing, feeling like everything is dissolving in the vibrating being, feeling like I am about to blow up or die, and sometimes visuals, like the stage before a breakthrough on 5-MeO (which I have had a few off, and it's very similar, though I have never broken through on either completely, nor with this method.. I still get spooked) I also experience feeling fuzzy and a nice calm sometimes after, feeling more awake. It can also be disorienting.. - I find you can also chose to stay with your body more on this method, and observe your body-mind system, if you don't go along with the feeling of dissolution, and you can go deeper into your body, feel the energetic knots, which may also just be helpful. - So here's some info on what I think happens.. All your insecurities, energetic suppression, negative conditioning and trauma's are stored in the muscles (this can be observed if you meditate, do bio-energetic exercises, or it's seen pressure point therapy sessions like this https://www.youtube.com/watch?v=-uyvhPpk04s)  After a full inhalation, you put internal pressure on the muscles along the spine, on the heart, in the head. And whereas these muscles are normally used to release back again, now they are staying expanded through force, which I think shocks the mind, and paired with having the intention to dissolve, you can a strong energetic opening to Self. I also found that if you resort to a negative state during such a rush, by thinking fearful thoughts and contracting into that idea, it can mess up the energetic flow a little bit and cause a (short) headache for example. Which is typical for everything in life, if you move into a more closed state, things get less harmonious (both inner and outer). So maybe there are risks (there are always risks to everything) but afaik, there should be no real risks to holding your breath for 2-10 seconds (albeit this is different: they did not find brain damage on a study on divers who regularly hold their breath for minutes) - So how it works: Sit down in a relaxed state, when you feel ready, take a deep big breath (see how much pressure you want to put on it, maybe don't go too hard (at first)), then relax, do nothing, and try to let go in the feeling of intensity. Also I like to use the app 'Meditation Breath - Pranayama', to do this as a guided meditation and use '9 seconds in, 6 seconds hold, 9 seconds out, 0 seconds hold', edit: with semi-full breathes. - Very interested in hearing your results.