They will make you a nervous wreck if you worry about everything that they do. King was sleeping so much when he was little, like the entire first night I had him, and was actually kind of difficult to wake up. He yawned constantly, like 3-5 times a minute, all the time he's awake. He still does, even in the middle of running around, he will yawn. Most of the time he makes an odd noise, like a rusty fence gate opening or closing.
I was sure there was something wrong, even though he was bouncing off the walls anytime he was awake, and could outlast any other pups and dogs he played with. I finally took him to the vet to get checked out, and before they even did anything with him, she said she doubted any dog that was as crazed as he was had any problems. She was right. He's going to be 12 in about 7 weeks, and had a lot of problems a year ago (Cushing's Disease), but he's doing fine now, and still sleeps more than any dog I've ever had, and is even harder to wake up then when he was young.