Cant fall asleep

I am what people call a "night owl." I sleep during the day, and work 12 hour shifts at night. Most times I can sleep through just about anything. Even my alarm clock and my family getting mad because it sounds through the house and Im still sleeping in my bed. hehe.
But sometimes I just cant fall asleep because I feel like my leg is being pounded by a hammer or something that makes it continually hurt. I have to raise my legs up on pillows and take a tylenol for it to go away. But I can never figure out what makes my legs hurt in the first place. Is it the blood pressure in them, or maybe it's the workout that I did the week before. ?? I dont know...
On other occations I just cant get to sleep and I spend hours thinking about a trillion things before I even start dozing off...but then its time to go to school and I had hardly even counted lamb #3. What is it that keeps us up all night. The test that I have that day, or maybe a personal issue like "why did I order the biggie size." I cant figure it out. I know that Im tired because I stayed up the whole night working so I just lay there wondering about how Im going to survive the next night at work and find time for school and sleep. So one day I heard about how you dont get the same sleep as most people do when they sleep at night due to the daylight and other inner stability issues. So I decided to try it by putting a huge blanket around my bunk bed to keep most of the light out. I call it "Fort Insomnia" hehe. But I am thinking of changing the name because it seems to help a whole lot. I dont know why, but when you sleep in the day, even if you get less hours of sleep at night in the dark, the few hours in the dark were better rested than the many hours in daylight. If anyone knows the reason to that fact, please let me know why.
But still, for many people, they still cant fall asleep even when it is dark and a thousand thoughts are going through their head. For them I believe that it may be an imbalance in their life either physically or personally, or an unresolved issue that just keeps them restless. But Im not a doctor and I really dont know the truth but if there is anyone out there that reads this and know the answer to solving insomnia, please help because this problem concerns thousands of people in many parts of the world.
-Jeremy