Well if you are eating to little it may cause you to get tired, but you need to eat VERY little compared to your body. I remember before I knew what I was doing and I was young I use to starve myself, I was sleepy all ay long b/c I had nothing in me to burn for gas.
If you are sleeping 12 hours a day you maybe sleeping to much. If you sleep to many hours you wake up and remain tired all day. Try working out a solid meal plan, post your current one here so we can help you out with it, and keep a set day. Sleep the same time every day and thats it. A solid 8 hours should be fine. The work your meals around that making sure you taking in the proper ratio's of P/F/C according to your weight.
"Only in dictionaries does SUCCESS come before WORK." -Alfred K. Henderson
Today I do what others will not so that tomorrow I can do what others cannot!