I get shortness of breath, too. However, I am an IV user. Sometimes I can't get enough air in my lungs to walk up a few stairs! In MY own opinion it's normal, well normal for using meth anyway, and I do agree it could have a bit to do with anxiety as well. If get a crap bag, it will give me a panic attack and it's hard to breathe. I feel like I just can't get enough air. Then I started messing up my breathing, which ends up being worse for me! Thankfully I've learned to control the attacks, so they don't go into full force. But yeah, sleep! When I'm up for a couple days it's defiantly worse! Just take it one slow breath at a time and figure out of it's worth it to you.. Good luck!