I dont know why this is happening, but when I wake up from my sleep, i seem to be more tired, and I dont know why this is. If I do over sleep this just makes me get a headache. For example i went to sleep last night at 8.30pm as was feeling tired, and woke up the next morning at 5am, which is more than enough sleep.

Why is this happening, and any tips on how to feel better when waking up.

I would suggest you do some stretching and drink a glass of water. Do you feel this way every morning? If you do, maybe you might need some medical check up.

There's such a thing as obstructive sleep apnea....your sleep gets interrupted due to sudden lack of oxygen...so when you wake up, you still feel tired and you find yourself sleepy during the day...you better get a medical check up.
OR perhaps you're just too stressed out lately that's why you feel tired even after sleeping...

You might just not be getting a restful sleep. I know sometimes when I have alot on my mind, I can sleep all night and wake up feeling like I haven't slept much at all.
Maybe you can try going to bed a little later in the evening and then you might wake up a little later.

This happens to me all the time and, for me at least, I've found that I wasn't exercising enough and wasn't eating right. How often do you exercise? It may have something to do w it if your bodys not gettin enough oxygen

Maybe you should sleep at a more regular shedule. Consider going to bed at anywhere between 10p and midnight then wake up at 8a. This sleepiness that you're feeling could just be your body telling you to sleep at another time of the day.

I already experienced this kind of feeling. But it is not often. I just notice that this happens when I have something on my mind, some thing that is bothering me. It also happens when I ate a heavy dinner before I go to sleep. So, now I don’t really go straight to bed after eating. I also drink lots of water before going to sleep.

Another thing that I learned about in Anatomy classes is sleep cycles. Apparently the only way you feel rested is when you wake up at a certain time during the sleep cycle. Sorry, I don't remember... but I think you should look it up, it may help you