The belief in human vampires, dead persons who come from their graves at night to suck the blood from living people, still influences burial customs and the siting of graves in some regions of eastern Europe, Greece and the Mediterranean. Children and adults are terrified of graveyards and the dead because of such superstitions, and extension are afraid of the dying who thereby become objects of repulsion to be avoided, even if a loved member of the family.
A rare disease called porphyria has been postulated as the core of vampirism. Treatable today, victims suffer extreme sensitivity to sunlight, and in the past had to stay indoors ('the children of the night') as exposure caused disfiguring by sores, scars, extreme hairiness, possible loss of extremities (noses and fingers), and stretched skin of the lips and gums, yielding fang-looking teeth. The belief in vampires may have instigated imitative behaviour among the psychotic, especially after wide dissemination of films based on Count Dracula. In modern Europe two instances of insane killers are recorded who were inspired by the film character. In occult and spiritualistic circles there is a belief that sensitive people may be drained of vital energy, under certain conditions, by disincarnate humans or other invisible entities. The term vampirism has been attached to a theory that one living human, in a variety of ways, can draw psychic or biological energy from another.