Three seperate and perhaps related items ...
1) When I use a foam roller under my SI joint, I feel the left side drop with a small pop. It's pleasant and it feels like it relieves some minor tension.
2) When the foam roller is under the hip and raising it about 6-7" off the ground it feels so much easier to breathe.
The air comes in to my lungs and fills them deeper. Breathing in and out is slower and almost fully diaphramatic it feels.
I don't know if it's the angle of my hip, or the lower back or rib cage being elevated but I'm wondering if this points to some kind of restriction somewhere and is there an indication that something could be stretched to breath like this normally?
So relaxing I think I may stay in that position more often.