Aneros fixes my erection problems

For the past few months I've had some erectile isssues during sex or masturbation, some of it attributed to my use of opiates for my chronic pain. I either lose erection soon after penile stimulation or go flacid very quickly between changing sexual positions and find that I am unable to get erect again no matter how long I try afterwards.

So during one of my loss of erection moments I decided to just quit halfway into the masturbation and pull out the aneros isntead, I also added a small vibrating bullet to the tail, to my surprise the anal stimulation gave me an erection again at which point I stopped and continued the masturbation succesfully. So now I have made it common practice to use the Aneros whenever I lose an erection, but my question is how does this work ?