My experience is almost the same as AprilLove's. My Yorkie is now 6 months. When he was young, I left him by himself in the crate in kitchen at night. He would cry and whine like crazy in the middle of the night. It distressed both of us so much (and likely my neighbors too). Then I took his crate and parked it next to my bed at night. No more barking and whining. That was also where he would be if I was away from home. It was a good way to housebreak him as a result. He learned that the peeing and pooping is for outside. After a few months of this routine, I got him an xpen, left his crate in the xpen with the crate door open. He doesn't bark or whine much nowadays (in fact, he rarely barks anymore.. it's awesome! LOL). He goes into the crate by himself if he wants to nap. He does whine for a couple mins (but nothing unmanageable) if he sees me around the house but he's stuck in the xpen. But if I ignore him and don't let him out of the xpen, he stops whining. When I'm able to pay some attention to him, I let him out of the xpen. When he's out, he's usually attached at the hip with me lol... so adorable
I'm quite happy with his progress so far
