Put a "nice" note under their door letting them know that their dog is constantly waking you up, and if that doesn't work, do it again...I live in an apartment complex with dogs, dogs, and more dogs (and have one also) but sometimes people don't realize their pet's a problem till you tell them - the guy that lives above us was keeping his "big" dogs caged for hours on end so all they did was bark and howl incessantly - after my third note, he did something different, they still go at it, but much less frequent - worth a try...