The sun is a symbol of warmth, light chasing away the darkness and the scary things that creep up on us when we cannot see clearly, a symbol of life and restoration. All of these are things that traditionally a vampire fears because they are no longer a part of his life and never will be again.

Vampires seek out the warmth of the human condition, the warm blood flowing through veins because their bodies have stopped functioning. Without the flow of blood through the body, there is no warmth to the flesh. The sun is the greatest source of warmth that there is, and a vampire cannot bear the strength of that warmth because of the chill of death that clings to them, just as the chill of death clings to anyone who dies, because the body naturally cools.

How many vampires would be successful in sneaking up on their victims if it was the bright light of day that they were hunting in? They need the darkness to hide themselves, because as humans fear anything that they cannot see or that moves in darkness, so they fear them. That fear can paralyze a victim, and so make it easier for the vampire to catch up with their prey.

Think about the winter time, when everything lies cold and dormant, and there is no new life. Nothing grows in the winter. The life cycles of animals are set to reproduce in the spring, when the sun has returned to lengthen the days and make things warm and bright. Vampires do not contain that spark of life. They do not share in the delights of a bright sunny day because everything is vibrant and alive, and that is something they can never be again. Their life ended and they were cursed to continue on after death, still moving in a cold dead body that cannot rest and go on to its eternal reward or the possibility of rebirth.

Vampires long for the things that were taken from them. Warmth, hope, peace. They cannot rest, because their need for blood in an attempt to sate themselves, to make themselves feel as they once did, is a powerful driving force that compels them to continue their nightly dance in the darkness. If they welcome the sun back into their lives, they will end their lives forever. No one ever wants to die, and a vampire’s desire to continue living drives them to do whatever they have to to continue living, even if that means warring with themselves internally.