Cortisol Dysregulation in Chronic Insomnia: A Critical Review

Insomnia-related hyperarousal has been associated with hypothalamic-pituitary-adrenal axis dysregulation, with cortisol identified as a potential neuroendocrine mechanism underlying persistent physiological arousal. Recent studies link dysregulated cortisol patterns to chronic insomnia severity, pre-sleep arousal, and sleep reactivity, but differences in demographics, research design, and cortisol measurement limit the direction and consistency of this relationship. Cortisol dysregulation is more precisely defined as HPA-axis dysregulation than as elevated cortisol, with potential abnormalities developing in basal concentrations, stress reactivity, or post-stress recovery. It remains unknown from past studies whether cortisol dysregulation supports the disorder, emerges as a reaction to chronic sleep disturbance, or increases susceptibility to insomnia. This review article critically assesses current empirical data and the methodological challenges associated with evaluating the extent to which cortisol dysregulation perpetuates hyperarousal in chronic insomnia.