The classification of diseases represents an important, yet often enigmatic, process. This is especially true in the case of stress-related diseases. Until the 1980s, stress-related diseases were categorized on the basis of the target organ system affected. A merger of 20 years of clinical data with research and theoretical formulations from the neurosciences gave us the opportunity to reformulate, or at least add a fresh perspective to, the understanding of the nature and treatment of stress-related diseases. Based upon over two decades of research and clinical trials, one such reformulation is presented here. It is contended that many psychiatric and somatic stress-related diseases are but manifest variations on a theme of limbicogenic neurological hypersensitivity and resultant pathogenic arousal. The resultant stress-related diseases are, therefore, viewed as "disorders of arousal." From the reformulation offered herein emerges a neurologically-based rationale for the clinical use of the "relaxation response" in the treatment of stress-related diseases.