Can chronic stress flatten HPA signaling and lower morning cortisol with DHEA-S?

Prolonged exposure to chronic stress shifts the hypothalamic-pituitary-adrenal (HPA) axis from initial hyperactivity to a state of systemic hypoactivity. This transition results in diminished hormone outputs, blunted diurnal rhythms, and distinct downstream clinical consequences.

Clinical and physiological shifts

• Flattened diurnal cortisol: Long-term stress downregulates HPA signaling, resulting in a blunted morning cortisol awakening response (CAR) and a flattened diurnal cortisol slope rather than a simple high-cortisol state.
• Depressed DHEA-S levels: Chronic allostatic load and severe burnout consistently correlate with lower circulating DHEA-S and an elevated cortisol-to-DHEA-S ratio, a pattern highly relevant when evaluating endocrine health in older adults.

Molecular and systemic mechanisms

• Central HPA downregulation: The shift to a low morning cortisol pattern is driven by pituitary downregulation, suppressed corticotropin-releasing hormone (CRH) secretion from the paraventricular nucleus (PVN), and altered glucocorticoid receptor sensitivity.
• Enzymatic pathway redirection: Rather than a physical depletion of shared precursors (the disproven "pregnenolone steal" hypothesis), lower DHEA-S is caused by sustained adrenocorticotropic hormone (ACTH) signaling. This central signaling alters local adrenal enzymatic pathways, prioritizing glucocorticoid synthesis over androgenic pathways.
• Downstream health outcomes: A blunted CAR and low morning cortisol directly contribute to morning fatigue. Additionally, the loss of normal circadian cortisol rhythms leads to insufficient glucocorticoid-mediated anti-inflammatory control, resulting in elevated systemic inflammation.

Bottom line

• Chronic stress eventually flattens HPA axis signaling, producing low morning cortisol and decreased DHEA-S. This hypoactive endocrine state is driven by central receptor downregulation and shifted adrenal steroidogenesis, resulting in morning fatigue and increased systemic inflammation.