Could be depression. If you have other reasons to suspect you might be depressed, get it checked it out. I'm not saying you are -- just saying that this kind of disturbed sleep pattern is often one symptom.
It could also be your cortisol is screwed up. Ideally, cortisol should be higher in the morning (makes you wake up and get going) and low later in the day. If you do stuff like train heavy late in the evening, you could be causing a surge of cortisol when you don't want it.
At night your cortisol should be lower and your melatonin levels should be higher, making you relaxed and sleepy. Bright lights, including TV/monitor screens, suppress melatonin. This is why you often hear the advice of making sure the room you sleep in a very dark room.
Maybe try switching off the TV and computer earlier in the evening and dimming the lights before you intend to go to bed. Also, when you do manage to wake up early, get yourself outdoors as soon as possible. Bright sunlight early in the day will help reset your sleep/wake cycle.