I have a 10 month old male havanese that pees while he sleeps most of the time.
Is there a underlaying problem or is it just part of growing up just like humans.
He doesn't pee or poop in the house so I'm not sure why this is... please advice.

Does he pee a lot? Or just a little bit?

You might want to talk to your vet. He could have some type of infection. Boys don't usually have those problems, typically it's the girls. But definitely get him check out to be on the safe side