My lab Star does the EXACT same thing!! Besides being a very active dog (even after 2 hours of flat out running, retrieving, swimming, agility classes twice weekly etc. daily) she only wants to sleep for 4 or 5 hours nightly!! There isn't a dog on earth that gets more exercise! And, she has become so accustomed to waking up with me at 5am for work, and having an early breakfast, that she figures if 5am is good, then 4am is better!!! Usually, she starts whimpering and pleading about 2 or 3 am. to get up and play. She actually drops a ball on my chest. I have to put her out of the bedroom and ignore her. (Not easy) That usually works. But by 4:30 or 5am, she starts again!! Any ideas Carrie?????