Can I add my two cents to this post? I have an interesting theory myself as well.

Recently I've "mastered" a technique where I can stay in a lucid vivid dream for a very long time. It's that whenever it seems I'm going to loose "dream clarity" I somehow automaticaly subconsciencely loose lucidity for the time in which is easy to get excited or loose a clear view. When it seems to be ok I gain lucidity again. I still don't exactly don't know how this works but it has something with the believing that this will work and it works for me. Just today I've had a few false awakenings in a pretty long lucid vivid dream.

By the way, the breathing actually works. I've experienced it a few times in the past. It's great for waking yourself up from a nightmare.