So, I've found that in many of Laberge's exercises, he says "lie on your back or right side". I've noticed long ago that I'm more comfortable and have a much easier time falling asleep when lying on my right side (i.e. right shoulder on matress, not "facing towards the right"). Why is this the case? I think it may be because your heart is higher up, so it isn't getting crushed, and has an easier time circulating blood, but not sure...