Have you heard of the Buteyko system of breathing? Check it out because shallow breathing is not necessarily a bad thing. What is important is levels of Carbon Dioxide because these need to be high in order for your blood chemistry to be right. If they are not paradoxically your body gets too little oxygen from your bloodstream.
Deep breathing can sometimes be overbreathing. If you ever feel spacey deep breathing you are in fact starving yourself of oxygen by breathing too much.
I went on a Buteyko course and it really helped me, reducing my anxiety levels considerably
Hope this is of some use.
Katey
