Where do the nocturnal erections go?

Even though there are a few threads dealing with nighttime erections, I haven’t found the specific answer I’m looking for. When I began using a CD overnight a couple of months back, I was rousing myself four or five times each night because of uncomfortable attempts at getting hard. After a few weeks passed, this happened less often. Recently, over the last fortnight, I usually only wake up once, with one or two nights seeing it happen twice. These episodes typically occur around 5AM, suggesting my sleep has become lighter. The other night was special because I didn’t stir at all from an erection. Here is what I want to know: Is my physique slowly adapting to the attempted erections and simply letting them pass without waking me up? Or is my subconscious mind figuring out that resisting the cage is futile, so it stops trying? I am eager to understand what is really going on. Aside from sleeping sheetless with an infrared camera aimed at the relevant area, I don’t see another method to verify this, do you?