When we talk about stress, we almost always think of the same things: work, deadlines, responsibilities, and the infamous mental load. And yet, from the body's perspective, stress has nothing to do with a specific context. It's not a situation; it's an adaptive response. Walter Cannon, a physiologist who pioneered the study of the fight-or-flight response, laid the foundations of this concept in 1932 in *The Wisdom of the Body*, and Robert Sapolsky, a neurobiologist, further developed it in the context of modern chronic stress.
How the body reacts to a perceived demand
Stress is the body's reaction when it perceives a demand greater than its current capabilities. A threat, pressure, a requirement. And that demand doesn't have to be psychological. It can be physical, biological, emotional, cognitive, or environmental.
For the body, there is no difference between modern stress and invisible stress. Neuroscientist Stephen Porges explains this through neuroception: an unconscious, subcortical neural process that continuously assesses the safety of the environment without conscious participation. It doesn't evaluate, interpret, or judge. It responds.
The invisible stress that you don't always feel
That's why stress often doesn't feel like stress. It's not accompanied by nervousness or obvious anxiety. It can creep in silently, gradually, almost as if it were normal. Bruce McEwen, a neuroendocrinologist, extensively documented this: anything that forces the body to expend energy to maintain equilibrium is stress, even if you're not consciously aware of it.
A deficiency in magnesium, iron, iodine, or protein is stressful. Sleeping too little or poorly is stressful. Unstable blood sugar is stressful. Slow, heavy, or incomplete digestion is stressful.
The impact of the modern environment on the nervous system
Chronic exposure to artificial light at night is stressful because it disrupts circadian rhythms and melatonin production. Constant noise, notifications, and screens left on all day are stressful for the nervous system. An environment lacking natural light, movement, and contact with nature is stressful. A sedentary lifestyle is stressful. A lack of secure human connection is stressful.
Unexpressed emotional stress is still stress. So are chronic fear, persistent guilt, and constant inner pressure. Rigid beliefs, constant self-criticism, and a sense of meaninglessness act as genuine physiological burdens. Even practices considered healthy can become stressful when they don't respect one's natural state.
The biological pathways activated by any form of stress
All of this has something in common. No matter what form stress takes, the body always responds by activating the same major biological pathways. The sympathetic nervous system kicks in. Cortisol and adrenaline levels rise. The thyroid gland is involved. Reserves are mobilized. The body does what it knows how to do to survive.
McEwen described it as allostatic load: the cumulative cost of chronic adaptation. The problem isn't one-off stress. Living beings are designed to adapt. The problem is the accumulation of chronic stressors, often silent, often trivialized, that force the body to compensate relentlessly.
Understanding stress beyond superficial relaxation
Therefore, understanding stress isn't about learning to relax more or adding disconnection techniques to an already overloaded body. Understanding stress involves honestly examining which aspects of our lifestyle are constantly forcing our bodies to compensate, sustain, and endure.
And very often, the true source of stress isn't where we think it is. It's not in what's visible, obvious, or what we usually point to. It's in what the body has been silently trying to balance for far too long.
Sources and references
Cannon, W. B. (1932). The Wisdom of the Body. W. W. Norton. Physiologist, Harvard Medical School.
McEwen, B.S. (1998). Protective and damaging effects of stress mediators. New England Journal of Medicine, 338(3), 171-179. Neuroendocrinologist, Rockefeller University.
McEwen, B.S. (2007). Physiology and Neurobiology of Stress and Adaptation. Physiological Reviews, 87(3), 873-904.
Porges, S. W. (2011). The Polyvagal Theory. W. W. Norton. PhD, neuroscientist, Indiana University.
Sapolsky, RM (1998). Why Stress Is Bad for Your Brain. Science, 273(5276), 749-750. PhD in neurobiology, professor at Stanford University.
Sapolsky, R. M. (2004). Why Zebras Don't Get Ulcers. Henry Holt.