Stress makes us sick. And in the most literal sense of the word.
Weakened immunity or a system exhausted by stress
You get sick often and might think your immunity is weak. In reality, it would be more accurate to say it's exhausted. It might seem like it's malfunctioning, but very often that's not the case. What's happening is that it's on pause, even short-circuited, by another system that has taken priority: the stress system. Robert Sapolsky, a neurobiologist, clearly documented this in his work on the physiology of chronic stress.
The body facing a fundamental biological choice
The body cannot be on all fronts at once. It must choose between surviving an immediate threat or repairing, defending, digesting, and healing. And under chronic stress, this choice ceases to be a choice: the body becomes locked into survival mode. Bruce McEwen, a neuroendocrinologist, described this phenomenon as allostatic load: the cumulative cost of an organism that relentlessly compensates.
Neuroscientist Stephen Porges describes it from the perspective of polyvagal theory: when the nervous system remains in chronic sympathetic activation, the restorative functions of the ventral vagus nerve are inhibited. It's not that the immune system fails. It's that it's not allowed to act.
The stress axis: hypothalamus-pituitary-adrenal
Stress activates what is known as the hypothalamic-pituitary-adrenal axis. This axis releases cortisol and other hormones designed to mobilize energy for fight, flight, or action. In the short term, this mechanism is vital. But in the long term, it becomes destructive. Because to conserve resources, the body puts on hold what is not urgent: digestion, reproduction, and immunity.
It's a matter of biological hierarchy: it's better to face the lion than the bacteria. That makes sense. The problem is that nowadays our lions never disappear. Walter Cannon, a pioneering physiologist in the study of the fight-or-flight response, laid the groundwork in 1932 for what Sapolsky would develop decades later: the body responds to chronic psychological threats with the same biological machinery it was designed for acute physical threats.
Chronic stress: a mechanism that becomes toxic
Work, pressure, conflicts, shortages, overstimulation, constant news updates, lack of rest, fear of tomorrow. Our nervous system remains in a state of permanent alert. The result: immunity is chronically suppressed, defenses collapse, infections multiply, and inflammation becomes chronic.
Chronic stress is not simply psychological tension. It is a biological state of dysregulation. It reprograms the body's priorities, preventing it from repairing, eliminating, and defending itself. And as long as this cycle remains unbroken, no supplement, no medication, no plant can restore lasting health.
Restore internal security to restore immunity
Regaining a strong immune system is, above all, about relearning to feel safe. It's about calming the nervous system, freeing the body from this constant urgency, and giving it back permission to heal.
It's not about strengthening immunity, but about giving it back the place it always deserved.
Sources and references
Cannon, WB (1932). The Wisdom of the Body. WW Norton. Physiologist, Harvard Medical School, pioneer in the study of the fight-or-flight response.
McEwen, B.S. (1998). Protective and damaging effects of stress mediators. New England Journal of Medicine, 338(3), 171-179. Neuroendocrinologist, Rockefeller University.
Porges, S. W. (2011). The Polyvagal Theory. W. W. Norton. PhD, neuroscientist, Indiana University.
Sapolsky, RM (2004). Why Zebras Don't Get Ulcers. Henry Holt. PhD in neurobiology, professor at Stanford University.