What Is the Confusion With Cortisol?

Cortisol has many roles not only in mediating the response to stress but also in the circadian rhythm, and it does so by both genomic and nongenomic cellular and molecular mechanisms. Yet, it is common to associate cortisol only with stress and, in particular, with the negative aspects of stress even though we would not survive without it. This commentary provides a brief overview not only of the diverse roles of cortisol but also of how to measure it to get meaningful information in the context of other mediators of stress and adaptation and the concepts of allostasis and allostatic load and overload. In particular, the adaptive plasticity of the brain mediated by glucocorticoids and excitatory amino acids is discussed in relation to misconceptions about what constitutes brain damage. Thus the confusion with cortisol is that it does too many important things both positive and negative!