Basically if I sleep on my right side or on my back, I wake up gasping for breath. Sometimes the (presumed oxygen) problem is bad enough that my body will be shaking/trembling for a bit until I roll over or sit up and catch my breath. Last night I did a semi-waking thing when this was happening, and realized my lungs felt like they were barely expanding at all, and there was a tight feeling associated with it, like they couldn't expand. I always sleep on my left side, but often roll over in my sleep. And I never have any problems while on my left side, which makes me think this isn't a "anxiety" or adrenal/etc issue. And it takes a while (at least half an hour on my right side) before this seems to kick in. Any suggestions?