This all sounds very interesting. I know it's not asthma because I can do pretty strenuous exercise even when my symptoms are the most severe and, as you have pointed out, I can fall asleep fairly easily unless the symptoms are extremely severe.
To be more clear on this, this condition I experience is not what I would label as an "attack" in the truest sense of the word. Rather, my symptoms and this "condition" are present with me ALL the time. I have had this for over 15 years now and it's a CONSTANT thing. The difference is that sometimes (most of the time really) when I feel like I need a good breath I get it. The tightness in my chest is pretty mild but it's still there. The "attacks" (if you can call them that) are simply times that I can not get the deep, satisfying breath that I need. I am not sure what causes it. There is no correlation between my diet, exercise, anxiety, stress or fatigue. It's like I just start having a hard time getting a deep breath out of nowhere. Each time I try to get a deep breath and don't, the tightness in my chest gets more and more severe. My back starts to ache between my shoulder blades and yawning is excessive. I can be right in the middle of a business presentation in front of 15 people and start yawning constantly...it's embarrassing. Anyway, once I DO get the deep, satisfying breath, the pain in my chest and back subsides and the yawning stops....for about 2-3 minutes...then the process starts all over again.
About a month ago I went through about a 2 week period where the condition was very severe and I gasped for air morning, noon and night. I twisted, laid flat, stood up, sat down...did everything I could to get a good breath but they were few and far between. Then, all of the sudden, I woke up one morning and, while I could still feel some moderate tightness in my chest, the breathing came easier so the yawning was infrequent and I was back to "normal". I wasn't under any stress...nothing major going on at home or work...my diet was about the same and my exercise level was consistent.
Right now, for example, I have mild tightness in my chest and I have even yawned a few times to get a good breath. I am able to, however, get that deep, satisfying breath I need each and every time. So, it keeps the condition at bay. It's when I can't get that deep, satisfying breath that the condition starts to worsen, the pain starts, yawning becomes more frequent...