Cortisol

Cortisol is the primary glucocorticoid hormone in humans, secreted by the adrenal glands under the control of the HPA axis. It serves multiple functions: mobilizing energy in response to threats, regulating glucose metabolism, modulating the immune system, and participating in the sleep-wake cycle (following a circadian pattern: peak in the morning, minimum at night).

In the context of trauma, cortisol becomes a key biological marker. A paradoxical finding has been documented: patients with chronic PTSD do not exhibit elevated cortisol as might be expected from a sustained stress response; on the contrary, they show decreased basal cortisol and an altered feedback response. Yehuda and colleagues documented this pattern in both Holocaust survivors with PTSD and —notably— in their directly untraumatized children.

Beyond the laboratory, cortisol alterations manifest clinically as hypervigilance, difficulty resting, sleep problems, inexplicable fatigue, and vulnerability to infections. The body has its own indicators, and cortisol is one of the most measurable.

Citing cortisol in the context of the systemic approach allows us to anchor subjective experiences of transgenerational stress in a biochemical variable that can be measured in saliva, blood, or hair.