Everyone experiences stress at times, but how well we handle it varies. Curious about the mechanics behind it?
You can sense stress building: your heart races, palms sweat, and you're hyper-alert.
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Our bodies rely on two primary stress systems. The autonomic nervous system includes the sympathetic (fight-or-flight) and parasympathetic (rest-and-digest) branches. These kick in during acute stress, like being put on the spot in a meeting.
"The parasympathetic system maintains balance at rest," explains Anja Huizink, Professor of Clinical Developmental Psychology at Vrije Universiteit Amsterdam. "When stress hits, the 'vagal brake' lifts: parasympathetic activity drops, and the sympathetic system activates—raising heart rate, quickening breath, and causing sweaty hands." This 'fast' system enables immediate action, she notes.
The second system, the hypothalamic-pituitary-adrenal (HPA) axis, reacts more deliberately. Unlike the reflexive autonomic response, it involves awareness: 'This situation overwhelms my skills.' It's ideal for prolonged stress.
The HPA axis tempers the autonomic system to conserve energy, preventing prolonged hyper-alertness. Huizink adds: "It dampens the sympathetic activity, allowing parasympathetic recovery, and triggers restorative processes."
It starts in the hypothalamus, activating the pituitary gland, which stimulates the adrenal cortex to release cortisol—the key stress hormone, measurable in hair or saliva. Cortisol mobilizes glucose and cholesterol for energy.
