On second thought, I can remember having oversleeping problems before joining the military, too. And before my six years of going to college and working in the civilian world. And in high school, too. And I distinctly remember how depressed I felt after oversleeping.
Your REM pattern is messed up. Think back to the last time you had a real dream. There is something that is keeping you “en guard”. I still go through this most nights, but it is getting better. Good Luck!