A word of advice from someone who has been there and done that!
It IS possible to retrain your bladder to empty itself while you are asleep, but it takes a really concentrated effort and a good deal of patience and persistence to achieve night time incontinence. If you are thinking of retraining your bladder to let go while you are asleep, be VERY sure that this is what you want because once you have trained yourself to wet while asleep, it is VERY, VERY difficult to regain control again. Some folk have even found it impossible to learn to be dry again at night, and in some cases it has also led to daytime incontinence as well. Think VERY carefully before you make the decision to become a bedwetter. If, after careful consideration of all the related consequences, both pro and con, you decide that this is what you TRULY want, then I say "GO FOR IT!" and may you enjoy the results.