I have been having wet dreams since about 8. Some docs say that it is the body releasing the sperm/semen when you are full of it.
Mine usually happens with sexy dreams or dreams where you have to pee like a race horse.
Before I was sexually active used to pump/ejaculate which would release the “load”.
With marriage usually get enough in bed to take care of the problem, unless we are apart then it back to Mary and her 4 sisters.