Stress isn’t just uncomfortable, it’s an immune insult

4 Sept

What really happens to your body when life gets hard and why the stress-immune connection is a factor you shouldn’t ignore

If you live with an autoimmune condition, you’ve possibly noticed the pattern. A brutal few weeks at work, a bereavement, relationship difficulties, a season of relentless pressure with no real let-up… Then, almost on cue, your body decides it has had enough. A flare. A crash. Symptoms that had been manageable suddenly aren’t.

You might have wondered whether stress really does make things worse, or whether that’s just something people say. The answer, however, is actually pretty clear. There is a direct, well-established connection between your nervous system and your immune system, and once you understand how it works, this pattern stops being a mystery and you can start getting back in control.

In this article, I’m going to walk you through that connection in plain language. So you can understand what is actually happening in your body when you are under pressure, how quickly the immune system responds (the answer may surprise you), why a chronically activated nervous system creates a chronically activated immune system and what you can start doing differently with that knowledge today.

a man on his computer covered in stress related notes

Does stress really affect autoimmune disease?

Maybe you’ve been told by a well-meaning doctor to “reduce your stress” and found that advice so unhelpfully vague that you filed it somewhere next to “drink more water” and moved on. Maybe you feel a creeping guilt every time your autoimmune symptoms flare during a difficult period, as if you have somehow done this to yourself. Maybe you have spent years treating your emotional life and your physical symptoms as two entirely separate problems with two entirely separate solutions and something has always felt slightly off about that framing.

What the science of psychoneuroimmunology (PNI) tells us is that the separation was never real. Your nervous system and your immune system are not two departments that occasionally send each other memos. They are in constant, direct, two-way communication and how they talk to each other has a direct impact on your health.

My own story: the camel’s back and what was already wrong with the camel

So, cards on the table, I think it would be fair to say that I am a perfectionist in recovery. An eldest child, with an impossibly high threshold for what counts as “good enough”, and for a significant period of my career, I worked for one of the most toxic bosses I have ever encountered (sadly also a woman). Daily humiliation was standard. My work was regularly ripped up in front of me and thrown in the bin. Eighteen-hour days were standard. Being the only woman (other than the toxic boss) on a floor of over 200 men, watching colleagues regularly reduced to tears in an open-plan office as a routine demonstration of power. Then simply swallowing it all, day after day, because showing any kind of crack would feel like defeat (or at least that was the promise I had made to myself).

My nervous system, for that entire period, was in a state of permanent high alert. Not occasional stress, but chronic, unrelenting, background-level threat response. Fuelled unhelpfully by sleep deprivation, poor food, too much alcohol and the very particular pressure of performing total composure, while internally bracing for the next blow.

Then I went on holiday. A long-overdue break in the Maldives, the kind that’s supposed to be relaxing and restorative. I managed to get food poisoning. For most people, that would be unpleasant and temporary. However, for me, carrying an HLA-B27 gene (a genetic marker that increases susceptibility to certain inflammatory joint conditions) an immune system that had been running on cortisol fumes and office takeaways for years, coupled with the gut permeability that stress causes, that gut infection was the last straw. Ankylosing spondylitis took hold within just a matter of days.

I think of it using a phrase from one of my mentors: the gut infection was the straw that broke the camel’s back, except the camel already had arthritic knees and some foot problems. The infection was the trigger, but the years of chronic stress, coupled with poor lifestyle had already done their work on the internal foundations.

The stress-immune connection: how your nervous system affects immunity

Psychoneuroimmunology is a field of science that looks at the relationship between psychological experience, the nervous system and the immune system. The term sounds horrendously complicated, but the central finding is elegantly simple: the brain and the immune system are directly connected and influence each other continuously.

One of the most striking early demonstrations of this came from a study of actors. Those who spent a day performing emotionally negative, depressive scenes were measurably immunosuppressed by the end of it. Those performing uplifting scenes showed improved immune responsiveness. No infection or pathogen, no change in diet or sleep. Their emotional state alone was sufficient to change immune function. The immune system, it turns out, is listening to everything. [1]

The mechanism runs through the body’s central stress response system (the HPA-axis) originating at the brain. When the brain perceives a threat (real or imagined, physical or psychological) it triggers a cascade: the hypothalamus releases corticotropin-releasing hormone (CRH), which signals the pituitary to release ACTH, which in turn tells the adrenal glands it’s time to produce some cortisol. Cortisol is often described simply as the stress hormone, but it is also a powerful immune controller. In the short term, it mobilises immune cells and primes the body for protection. Over time, however, when the cortisol signal neeeeever switches off, it starts to dysregulate the very system it was designed to support. [2]

stressed woman with a colourful brain full of cogs above her

How quickly does stress impact your immune system?

Faster than most people realise… The innate immune response to acute psychological stress begins within minutes to hours of the stressor arising. Studies using acute stress protocols in humans (public speaking tasks, controlled threat situations) have shown rapid increases in natural killer cell numbers, changes in leukocyte distribution and a measurable rise in pro-inflammatory chemicals (cytokines including IL-6 and TNF-alpha). [3,4]

So after a bad day at work, a heated argument, a terrible night’s sleep after weeks of worry… the immune response does not take a week to catch up, it is already moving. The body doesn’t see the difference between a physical threat and a psychological one (yup, your boss’ nasty email and a tiger are essentially the same in its eyes).

In laboratory studies using a protocol called the Trier Social Stress Test, healthy volunteers were simply asked to prepare a short speech and carry out mental arithmetic in front of an evaluating panel. No physical exertion or danger, no external threat of any kind, just the nail-biting anticipation of being judged… Even so, cortisol levels reliably rose 2-4x above baseline, alongside measurable changes in ACTH, growth hormone, prolactin and heart rate. [5] The implication for anyone managing a high-pressure job, a difficult relationship or a prolonged period of uncertainty is relevant and measurable. Your body doesn’t need a tiger, or even a deadline, the perception of just being judged is enough and in today’s society that has a myriad of implications.

four judges at a desk holding up different numbers

The part that matters for understanding autoimmunity is between acute and chronic stress. Acute stress (a short, contained challenge) can temporarily strengthen immune surveillance: the body mobilises resources and then recovers. Chronic stress on the other hand (unrelenting, unresolved, with no real recovery window between bouts) is where the damage tends to accumulate. Chronic stress leads to impaired HPA-axis feedback, glucocorticoid receptor resistance and a paradoxical cortisol dysregulation that promotes a persistent inflammatory state. [2] Ironically, the system that was supposed to resolve inflammation becomes part of what sustains it.

“A hypervigilant nervous system creates a hypervigilant immune system”

When the nervous system is in a state of chronic threat activation, it does not just affect mood, sleep or digestion. It creates the conditions for immune ‘hypervigilance’. An immune system that is primed to react, prone to overreaction and less precise in its ability to distinguish between genuine threats and safe tissue (i.e. your own body).

Chronic stress is a significant driver of the key inflammatory initiator and amplifier in the immune system (something called NF-kB). Chronic inflammation is sufficient to affect the brain and in turn affects the chemistry driving stress responses. Stress drives inflammation…inflammation drives stress. For anyone living with an autoimmune condition, this physiological loop has real, measurable, biological consequences. [2]

The thymus gland, where immune cells mature and where potentially autoreactive cells (the ones that can mistake our own tissue) are meant to be weeded out before causing problems, is also directly affected. Cortisol literally shrinks the thymus over time and can impair this quality-control process, reducing the precision with which self-reactive immune cells are identified and removed before they can cause harm. [2]

There is also the cortisol awakening response to consider. This is the natural spike in cortisol that occurs in the first thirty minutes after waking and it plays a specific role in immune regulation and in the thymic weeding-out process. A flat or dysregulated awakening response (common in people with chronic stress histories) has been associated with an increased risk of autoimmune disease development and worsening of existing conditions. [6] It is one of the reasons that sleep quality, morning light exposure and a consistent wake time are not just random lifestyle suggestions in the context of autoimmunity, they are wonderfully simple and valuable inputs to immune regulation and safety signalling.

The words you use to talk to yourself matter…

This one tends to get filed under ‘self-help’ rather than immunology, which is a shame, because the research is incredibly useful.

the word 'kindness' in a book with other small words around it

Psychologist and researcher Kristin Neff has spent two decades studying self-compassion and its physiological effects. Her work, and the wider body of research it has generated, shows that harsh, self-critical internal language activates the same threat response in the body as an outside stressor. The inner critic that tells you you’re ‘not doing enough’, that you ‘should have handled that better’, that you are ‘failing at recovery’, is a real biological signal, and the body responds to it accordingly, with elevated cortisol and measurable increases in inflammation. [7]

Self-compassion (treating yourself with the same respect you would extend to a friend) is associated with lower cortisol reactivity, reduced inflammatory cytokines and greater heart rate variability, which is a marker of a more flexible, well-regulated nervous system. [7,8] The physiological cost of chronic self-criticism in a body that is already managing an inflammatory condition is high, so let’s change the script.

If your inner monologue during a symptom flare-up runs something along the lines of “why can’t I just get this under control?” or “I should be doing better than this” or “I’m so frustrated with my dysfunctional body”, it is worth considering that those very thoughts are adding to the load your immune system is already dealing with.

Try these simple reframes:

Instead of “Why can’t I just get this under control?”, try: “Something has changed. Let me get curious about what might be contributing, without assuming I’ve done anything wrong”

Instead of “I should be doing better than this”, try: “My body is dealing with a lot right now. What does it need from me today?”

Instead of “I’m so frustrated with my dysfunctional body”, try: “My body isn’t trying to make my life difficult. These symptoms are information. Let me tune in for a moment and see what I can learn from them.”

When a flare feels as though it has come completely out of nowhere, try: “I may not understand this yet, but I don’t need to panic or blame myself. All symptom changes are information, not a personal failure. What might this one be telling me?”

What can you do to support nervous system and immune regulation?

Understanding that the nervous system is not a passenger in your immune health but a driver of it means you have more levers available than conventional medicine may tend to suggest.

The immune system is also, remarkably, educable in both directions. A landmark 1982 study demonstrated that the immune system could be conditioned, in the same way Pavlov’s dogs learned to respond to a bell. Mice with lupus were given a saccharin drink alongside an immunosuppressive drug. Once the association was established, the taste alone (with no drug present) reduced inflammation and symptoms almost as effectively as the drug itself. [9] The reverse is equally true: associations between sensory experience and safety can be built deliberately and those associations have measurable effects on immune regulation.

Start by creating a felt sense of safety through what you can SEE, HEAR, SMELL, TASTE and TOUCH; through the environment you curate; through the relationships you prioritise and the ones you draw boundaries around. These are legitimate and evidence-based strategies for moving the nervous system state that is shaping your immune environment. For example, using a specific fragrance you love (shout out to Norfolk Natural Living’s toxin-free scents), creating a habitual morning sequence, listening to a piece of music that consistently signals rest, are all things that condition your nervous system towards safety, and a nervous system that feels safer is, over time, an immune system that is less primed to attack.

This is why, in my work with clients, the nervous system and stress history sit alongside diet, gut health and immune biology as core parts of the picture. Addressing the immune system without understanding what the nervous system has been, and continues to be going through is, at best, only looking at part of the picture.

In summary

If you’ve skipped to the end, this article covers the important premise that the nervous system and the immune system are not separate systems. They are in constant, direct, two-way communication via the HPA-axis and a cascade of stress hormones and immune signals.

The immune system begins responding to psychological stress within minutes to hours. You do not need a physical stressor to generate a full physiological stress response, as the Social Stress Test research makes clear. The body responds to perceived threat in a similar way regardless of its source - email from the boss…or tiger.

Chronic stress is different from acute, short-term stress, and creates the conditions for immune hypervigilance: a system that is more reactive, more inflamed and less precise. Stress drives inflammation; inflammation drives stress. For anyone with an autoimmune condition, understanding this loop is important.

The way you speak to yourself has measurable immune outcomes. Harsh self-criticism activates the threat response. Self-compassion reduces cortisol reactivity and inflammation markers. Think of your inner voice as part of your immune health toolkit and talk kindly to yourself.

The immune system can be conditioned towards safety, just as it can be conditioned towards reactivity. Multi-sensory rituals, environmental cues and regular nervous system practices are all great tools.

One final word. None of this places the responsibility for your diagnosis at your door, it’s just helping to place more understanding and options in your hands.

Ready to look at the full picture?

If any of this has resonated with you and particularly if you recognise the pattern of symptoms flaring under pressure, or feeling as though your body is responding to something the doctors haven’t quite accounted for, I would love to have a conversation.

In my work, we look at you as a whole, because healing doesn’t happen one body system at a time. If you are ready to explore what a root-cause approach could look like for you, click here to book a chat.

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