He is still very young... night-time "dryness" is something that is not fully attained until even 7 years old. It is biological based development. So, he could still have night-time diapers on, for bed. Even Kindergarten kids still wear night-time diapers at night, for example. Normal.
He has not been potty trained for very long. It takes time. They will not attain peeing/pooping/AND night-time dryness and going to the toilet at night themselves all at the SAME time. It occurs in stages. Gradually.
So, you are still at the beginning of potty training. No rush. Yes, it is a slow process.
Actual ability and night-time dryness expectations (from the parent) are 2 different things. If a child wets at night or at naps, which is normal still... then just use waterproof bed-pads under him to make clean up easier, if their diapers leak. That is what I do.
Mostly, do not "expect" a child, at this age... to just get up at night and go to the bathroom at will, perfectly and to not have accidents. Again, it takes even up until 7 years old, for night-time dryness to occur. But in the mean time their bodies and their ability will mature, and one day they will "master" it. So until then.... take the night-time potty expectations separately. They are still trying to daytime potty train and have not mastered that portion of it yet. So that is only the 1st stage of potty training.
Potty training occurs in 3 stages:
1) daytime peeing in toilet and ability
2) pooping ability in toilet and mastering it
3) night-time dryness and mastering it. (which is also for naps).
But keep in mind accidents will still occur. Normal.
My daughter was still wearing a night-time diaper until 5 years old. MANY kids do, even at this age. Per our Pediatrician, it is NORMAL.
Also as a side tip: a "car potty" is real useful for times a child needs to pee but you are in the car or on the road and no bathroom in in sight or you are stuck in traffic. We use one and it is a lifesaver. Here is a link:
http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3...
If he is wetting at naps, its okay. He can still wear a diaper for naps. My son who is 3, and my daughter at that age, still wore diapers for naps and night-time. They didn't get "confused" or regress... I simply explained to them that for naps and night-time... they have diapers, but daytime they have underwear. No stress. Gradually, biologically, they do attain dryness. And it also has to do with the myelin development of the nerves as well.
its okay. He is still so young, to be dry during naps/night-time.
Accidents still occur in even older kids. My daughter is 7. She has been potty trained since 2 years old. She STILL once in awhile has accidents at night. I don't think its a big deal. I always just have a waterproof bed-pad under her. Or when she is just SO tired... and sleeping so deeply, she doesn't even wake.
All the best,
Susan