I'm not sure what's wrong. I've read somewhere that the average human being is supposed to get 8 hours of sleep per night (on average). But regardless of what time I go to sleep, I end up waking up after approximately four hours.
Go to sleep at 11pm? Wake up at 3am.
Go to sleep at 8pm? Wake up at 12am.
Go to sleep at 2am? Wake up at 6am.
No matter what. With or without an alarm clock, I wake up after approximately four hours of sleep for some reason.
But I am getting a little tired, truthfully. There are times that I feel half-aware of my surroundings. And I don't feel like my mind or body is performing even remotely close to its limits.
On a side note: if I take any kind of sleep aid (and believe me, I can't bring myself to take more than one in any sitting) I sleep for an extended period of time (like 12 hours)... and somehow still feel drowsy.
I don't get particularly tired during the nighttime; it's only during the day that I feel slightly groggy.
A friend suggested that it might be some kind of mental issue that I'm experiencing, but I don't feel depressed in any way... although I'm far from experiencing any kind of elation either. I feel "grey", but I can still laugh and find enjoyment in things. It's just to a very watered down degree.