Regulatory Bandwidth: A theoretical integration of present multisystem stress-regulatory capacity

Allostatic load models have provided a framework for quantifying cumulative physiological burden, while developmental models such as adaptive calibration theory have clarified how stress responsivity is tuned across development. I propose Regulatory Bandwidth as a complementary construct for psychoneuroendocrinology: the organism's present coordinated regulatory capacity across interacting stress-responsive systems. Regulatory Bandwidth refers to the flexible range over which autonomic, neuroendocrine, inflammatory, and metabolic processes can adjust to environmental demand without functional destabilization. I argue that heterogeneity in stress-sensitive clinical presentations may reflect patterned narrowing or expansion of this coordinated capacity across systems rather than isolated dysfunction within any single domain. Integrating allostasis theory, adaptive calibration, immunometabolic coupling, and mitochondrial energetics, I formulate Regulatory Bandwidth as a dimensional, multisystem model of present regulatory capacity. The manuscript develops four falsifiable hypotheses with abandonment criteria concerning (1) functional stability as a function of regulatory margin, (2) multidomain comorbidity as coordinated immune-endocrine-metabolic state, (3) burnout, relapse, and functional deterioration as nonlinear state transitions preceded by early-warning signatures, and (4) recurrent regulatory configurations that may improve stratification beyond diagnosis alone. The model is operationalizable using indices such as heart rate variability, diurnal cortisol dynamics, inflammatory markers, metabolic indicators, and repeated measures of functional volatility. I outline a minimal empirical implementation pathway for cross-diagnostic cohorts and propose that Regulatory Bandwidth may serve as a stratification construct for testing when cumulative burden converts into instability. If supported, this framework would extend existing stress models by formalizing present coordinated capacity as a measurable dimension of multisystem regulation.