I’m looking for a vampire novel published between 1970-1989.
The plot revolves around a vampire who runs some kind of sleep disorder/research clinic on a college campus and uses that to cover for feeding (not enough to damage the subject). There is a detective, I think named Tosca, after the opera, who figures it out and confronts the vampire, who is a good guy. They maybe join forces to combat another vampire?  There is a sequel, where the main character has moved to the southwest. Help, please!