Thanks for starting this conversation! I often wonder if my sleeping position effects my j-pouch - I think it does.
On my back I am so-so. I try to stay that way if I can, because once in a while I can actually pass gas that way without "sharting".
On my right side I am OK for the most part. I don't feel any changes, but if I roll on to my left side I have to "go" within minutes (or less!). Very peculiar! I wonder if it is how my j-pouch is shaped that makes the difference on what side I sleep on. And if it isn't that, then I wonder what it is. I hope more people chime in to this conversation. I will interesting to see if there are any trends, or if it varies person-to-person.