A 35-year-old combat veteran presents with hypervigilance, exaggerated startle response, intrusive memories, and chronic insomnia 14 months after returning from deployment. He is diagnosed with post-traumatic stress disorder. The PMHNP reviews the neuroendocrine basis of PTSD to inform treatment planning. Which of the following best describes the characteristic hypothalamic-pituitary-adrenal axis finding in chronic PTSD?