Vampire Research
Vampires are folkoric and mythological beings, known in many cultures to be a demon, a corpse of a human being, that commonly rises nightly from its grave to prey upon the living and suck their blood.
In the middle ages, people began to slowly believe vampires existence as diseases and infections, such as Porphyria, Catalepsy and Anemia had caught onto people and the symptoms were distinctively similar with need for blood as a Vampire craving.
In the 18th century, the awareness of vampires spread all over Europe which lead to mass hysteria, to the extent of people physically stabbing each other with stakes and accusing others of vampirism, due to their great superstition.
Before the modern characteristics that we relate to vampires now, they were stereotyped as demonic monsters. Having monstrous teeth, hair and nails. They would also be involved in poltergeist activity, like the unnatural explanations of something pressing to you.
While most people can name several elements of vampire lore, there are no firmly established characteristics. Some vampires are said to be able to turn into bats or wolves; others can't. Some are said not to cast a reflection, but others do. Holy water and sunlight are said to repel or kill some vampires, but not others. The one universal characteristic is the draining of a vital bodily fluid, typically blood. This has caused Vampires to popular as writers can play with the rules.
Villagers combined their belief that something had cursed them with fear of the dead, and concluded that perhaps the recently deceased might be responsible, having come back from the graves with evil intent. Graves were unearthed, and surprised villagers often mistook ordinary decomposition processes for supernatural phenomenon. For example, though laypeople might assume that a body would decompose immediately, if the coffin is well sealed and buried in winter, putrefaction might be delayed by weeks or months; intestinal decomposition creates bloating which can force blood up into the mouth, making it look like a dead body has recently sucked blood. These processes are well understood by modern doctors and morticians, but in medieval Europe were taken as unmistakable signs that vampires were real and existed among them.