I would personally be opposed to trying to suppress nocturnal erections. It’s pretty well accepted by most experts that these are designed to keep penile tissues ‘nourished’ by periodically flooding them with blood, which is what happens during an errction. Without this, these tissues can start to degenerate over time, lose elasticity due to fibrosis & over time that could result in loss of erectile function - in other words, ED !! I’m pretty sure you don’t want that!
I’m also opposed to the practice of trying to rely on wet dreams for release - there are several studies showing that frequent ejaculation clears the prostate & associated glands of fluids that can become ‘stale’ & there’s strong evidence this may help prevent development of prostate cancer. Studies showed that men who had more frequent ejaculations had a lower rate of prostate cancer later on.
As for the sleep angle, it prbly isn’t doing too much harm, but I would not continue to do this for the 2 VERY big reasons I mentioned - Possible ED & Prostate cancer.
FYI - I am a prostate cancer patient myself, so I know quite a bit about this subject - what factors can increase the odds of getting it, the purpose of nocturnal erections, frequency of ejaculation, etc., having done quite a bit of research into these topics...