The Science
Cortisol is a steroid hormone produced by the adrenal glands in response to stress.
In short bursts, it is essential — mobilising energy, sharpening focus, and reducing pain sensitivity.
But when stress remains constant, cortisol production becomes unregulated, losing its natural rhythm.
Instead of rising briefly in the morning and tapering off at night, levels remain high — or swing erratically — throughout the day.
This disrupts nearly every biological system in the body.
1. Brain and Nervous System
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Prolonged cortisol exposure damages neurons in the hippocampus — the brain’s memory and emotional regulation centre.
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This leads to anxiety, poor concentration, and “brain fog.”
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Elevated cortisol suppresses serotonin and dopamine, contributing to low mood and loss of motivation.
The brain, interpreting constant stress as danger, struggles to differentiate between real and perceived threats — keeping the sympathetic nervous system (fight-or-flight) permanently active.
2. Hormones and Metabolism
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High cortisol antagonises insulin, causing blood sugar spikes and subsequent crashes.
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It promotes fat storage around the abdomen and alters thyroid hormone conversion, leading to fatigue and slower metabolism.
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In women, chronic cortisol imbalance disrupts oestrogen and progesterone balance; in men, it can lower testosterone and impair muscle repair.
This metabolic disruption is often the hidden driver behind weight fluctuations, poor energy, and accelerated ageing.
3. Immunity and Inflammation
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Initially, cortisol suppresses immune activity — useful in short-term stress.
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Over time, this suppression backfires, leaving the immune system dysregulated: less able to fight infection yet more likely to overreact.
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Chronic stress increases inflammatory cytokines (IL-1β, IL-6, TNF-α), fuelling autoimmune conditions and skin flare-ups.
This paradox — suppressed immunity and heightened inflammation — lies at the heart of many chronic health and skin disorders.
4. Gut Health
Cortisol slows digestion and reduces blood flow to the gut, impairing enzyme release and nutrient absorption.
The intestinal barrier becomes more permeable (“leaky gut”), allowing bacterial fragments into circulation, further driving inflammation and fatigue.
The gut microbiome shifts toward stress-adapted species, reducing microbial diversity and serotonin production — key for mood and motility.
5. Skin Health
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Cortisol inhibits collagen synthesis, leading to thinning skin and premature lines.
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It delays wound healing and impairs fibroblast activity.
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Excess cortisol stimulates sebaceous glands, triggering breakouts and inflammation.
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Chronic stress reduces antioxidant defences, increasing oxidative damage and visible ageing.
The result is skin that becomes dull, sensitive, and slower to recover — even with optimal topical care.
6. Cardiovascular and Mitochondrial Effects
Unregulated cortisol increases blood pressure, heart rate, and oxidative stress within vessel walls, contributing to endothelial damage and atherosclerosis.
At the cellular level, mitochondria are overstimulated, producing excess reactive oxygen species and less ATP — a process that mirrors chronic fatigue and early cellular ageing.
Restoring Regulation
Rebalancing cortisol is not about eliminating stress but restoring rhythm.
Cortisol should rise with daylight and fall towards night — a natural circadian pattern controlled by the brain’s suprachiasmatic nucleus.
To restore this rhythm:
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Sleep consistently – aim for darkness and cool temperature to promote melatonin.
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Morning light exposure – stabilises cortisol awakening response.
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Balanced nutrition – steady protein and complex carbohydrates prevent blood sugar-driven cortisol spikes.
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Mindful movement – moderate exercise reduces cortisol over time, while excessive training elevates it.
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Nervous system regulation – breathwork, massage, and relaxation therapies re-engage the parasympathetic response through the vagus nerve.
In Summary
Cortisol is vital — but only in balance.
When left unregulated, it shifts from protector to saboteur, accelerating inflammation, ageing, and emotional exhaustion.
When brought back into rhythm, it fuels resilience, clear thinking, and healthy skin repair.
Calm is not the absence of stress; it is the mastery of rhythm — letting cortisol rise and fall in harmony with life, not in battle against it.
