Summary: You will dream that vampires suck your blood because you can't cope with the high demands. Vampire is a frightening creature, which is generally regarded as a symbol of evil.
Psychology: Fear of feelings and sexual relations can also be manifested as vampires in dreams. People always have a fear of strange things, so those images often appear in dreams to express this fear.
Spiritual level: Life-threatening plots usually appear as vampires in dreams, and you may also like to fantasize about the evil world you are in.