I did not mean to be snippy; I was trying to take you seriously.
If you seriously crave blood, then you should evaluate it from all angles to get to the root of the problem. It is something /serious/ and there are way too many kids here claiming they /need/ blood to survive. Either they have issues or like to play around. I by no means like to tell people to 'seek a professional' as I feel they are a waste of money (and I've read too many instances of corruption). I do not like to suggest it but there is a possibility that this may be something serious.
I believe in vampires and I believe in mental illness and I am no dope. If you are new to the site, I apologize, but you'll learn very very quickly that this place is rampant with vampire claims. If you're not new, then you should be aware of the types of reactions these claims get. I'm not picking on you but I find it inappropriate to lie (if that is the case) about something that causes some people a lifetime of torment.
And some people are just more nocturnal than others. It got me into trouble when I was in high school and now in college as I can't physically fall asleep before a certain hour. If it is a problem, you can google 'foods to help you sleep' (cherries are the best... said an MSN article). Try exercising before bed or start winding down earlier than you do normally.
For bad dreams, you can weave a dream catcher or make a worry doll, which I have a recipe for (or they are readily available at most witchy shops). And if you are a fan of vampire shows they /can/ affect your dreams, just like watching too much StarGate or Spongebob or "The Machinist" one too many times ( XD guilty lol ).
Maybe if you give us some more details, like when it started, detailed description of effect on the body and such, we could be of better use.