How do i get him to stay dry??

Ok not sure if this is in the right spot, and if its not pls feel free to move it..

Well as many would know my ds has adhd my youngest boy, he is on ritalin to control himself during the day and he is also on catapres for night time due to not being able to sleep..
He needs these tablets at night cause if not he wont sleep till 1 am no joke he is jumping off the walls until it ends nasty and a massive brawl starts.. often with my elder ones going crazy cause they cant sleep etc..

anywhoo my ds is still in nappies at night as he is often in a deep sleep that a bomb wont wake him, so he is in no condition to get p and go the toilet.
i tried the other night to keep waking him every 5 hrs since i dont sleep till around 1 i could keep trying but he would practically have to be carried to the toilet sat on it, often nothing, and i would have to put him back in bed and then he wets the bed..

he is fine with them but i want him to be able to not have to have a nappy on.. but i cant not give him his tablet at night..
what can i do?? anyone??