The Immune System and Emotional Boundaries
How stress weakens not just the body, but the sense of self.
Chronic stress blurs the line between body and mind. Explore how psychoneuroimmunology reveals the link between immune health and emotional boundaries.
The Invisible Connection Between Body & Mind
Modern science increasingly supports what holistic traditions have suggested for centuries: the body and mind function as an integrated whole. When emotional stress persists, the body mirrors this strain in tangible biological ways. The immune system, once thought to be purely physiological, is now understood to be tightly regulated by psychological and neurological processes (Ader, Felten, & Cohen, 1991).
In this context, psychoneuroimmunology (PNI) has become a transformative field, demonstrating that emotions, stress hormones, and immune cells engage in constant dialogue. The body is not a passive responder—it listens, reacts, and adapts to our inner states. Chronic stress, therefore, is not merely a mental health issue; it represents a sustained biochemical signal that shapes the immune landscape over time (Segerstrom & Miller, 2004).
The immune system’s ability to discern self from non-self parallels our psychological ability to maintain boundaries. When we lose emotional clarity, we are more vulnerable—both to infection and to identity diffusion. The same stress that weakens physical defenses also erodes the borders that define who we are.
What Science Reveals About Stress & Immunity
The evidence linking stress to immune function is robust and longstanding. Pioneering work by O’Leary (1990) established that chronic psychological stress suppresses both innate and adaptive immune responses, and that the immune system may not “adapt” over time to prolonged adversity. This means that long-term exposure to stress hormones such as cortisol can lead to persistent vulnerability rather than resilience.
Subsequent studies have shown striking physiological outcomes. Littrell (2008) reviewed multiple findings demonstrating that vaccination is less effective in those under chronic stress and that wounds take longer to heal—a tangible reflection of how the body’s repair mechanisms falter under pressure. Similarly, Cohen et al. (1991) found that individuals reporting higher stress levels were more susceptible to the common cold virus when exposed under controlled conditions, showing that stress can directly influence susceptibility to illness.
Even autoimmune conditions, in which the immune system mistakenly attacks the body’s own tissues, are exacerbated by stress (Stojanovich & Marisavljevich, 2008). In these cases, the immune system’s confusion between self and non-self mirrors the psychological blurring that occurs when emotional boundaries collapse. The parallels are striking: both systems falter when the organism is overwhelmed.
When Emotional Boundaries Break Down
Emotionally, chronic stress narrows our window of tolerance—the capacity to regulate and recover from intense emotion (Siegel, 1999). Under constant threat, the nervous system stays on high alert, keeping the body flooded with cortisol and adrenaline. Over time, this hypervigilance changes how we perceive and relate to others.
Research on emotional regulation under stress suggests that vigilance and unconscious concerns distort perception and amplify reactivity (Ashkanasy, 2003). In professional contexts, this can manifest as exaggerated responses to criticism, heightened defensiveness, or distorted interpretations of neutral cues as hostile. These patterns often lead to what organizational psychologists describe as emotional contagion, where one person’s stress spills into collective environments, impairing judgment and performance (Barsade & Gibson, 2007).
In personal relationships, boundary erosion may appear as over-identification with others’ pain or difficulty saying “no.” Just as immune cells may fail to recognize what belongs to the body, an overstressed mind can lose track of what feelings, expectations, or responsibilities actually belong to the self. The result is exhaustion, self-doubt, and emotional depletion—the psychological equivalent of immune fatigue.
Healing the Boundary Between Body & Self
Healing begins with safety. When the brain and body no longer perceive threat, the parasympathetic nervous system can restore homeostasis and allow the immune system to recover. Mind-body interventions such as mindfulness, yoga, and cognitive-behavioural therapy have demonstrated measurable improvements in immune function and stress regulation (Davidson et al., 2003; Creswell et al., 2012).
From a psychological standpoint, restoring boundaries involves learning to differentiate empathy from enmeshment and care from self-sacrifice. Therapeutic work that integrates emotional awareness with somatic grounding helps re-establish a sense of internal coherence. As one becomes more attuned to bodily sensations, the dialogue between mind and immune system begins to harmonise once more.
Rebuilding these boundaries—biological and emotional—requires patience. The immune system cannot heal overnight, and neither can the self. But as the nervous system re-learns calm and containment, both begin to function as they were designed to: discerning, responsive, and resilient.
In essence, stress doesn’t just make us sick—it dissolves the edges that define who we are. Healing them is both a scientific and spiritual act: a return to wholeness.
Cutting Edge Thinking: Where Boundaries, Biology and the Self Meet
The newest research in psychoneuroimmunology (PNI) is reshaping how we think about the self—not as something purely psychological, but as a biological state maintained through continuous communication between the brain, immune system, and environment. Emotional boundaries are now being studied not just as psychological constructs, but as physiological networks that can be measured, disrupted, and repaired.
Immune-to-Brain Signalling & the Sense of Self
Recent findings highlight that immune activity affects far more than inflammation or infection—it influences mood, motivation, and self-perception. Bower and Kuhlman (2023) describe how inflammatory signals interact with brain regions responsible for arousal, social connection, and cognition, shaping how we perceive safety and belonging. In this view, the immune system acts as a boundary organ for the self: it helps determine which internal and external experiences are safe to integrate and which are threats to integrity.
When immune signalling is dysregulated, people often experience emotional flattening, social withdrawal, or hypervigilance—symptoms commonly associated with chronic stress, trauma, or burnout. These patterns suggest that a weakened immune “filter” can translate directly into a weakened psychological one.
Microglia and the Brain–Immune Interface
At the cellular level, new work on microglia—the brain’s resident immune cells—offers a fascinating bridge between biology and psychology. Under chronic stress, microglia become overactivated, reshaping neural circuits related to emotional regulation, empathy, and social behaviour (Calcia et al., 2016; Johnson et al., 2024). This means that long-term stress can physically alter how the brain perceives interpersonal boundaries and threat cues.
In practical terms, when the brain’s immune cells remain in a state of alarm, we may interpret neutral expressions as hostile, overanalyse social feedback, or feel emotionally “raw.” These are not simply cognitive distortions—they’re neuroimmune responses that reinforce emotional fragility.
Duration, Adaptation, & Immune Resilience
While short bursts of stress can strengthen immune readiness—a concept known as hormesis—chronic, unrelenting stress exhausts this adaptive capacity. Khandaker and Dantzer (2022) note that prolonged inflammation can shift the immune system into a maladaptive state, where it no longer distinguishes between transient challenges and existential threats. This mirrors psychological burnout, where boundaries become either rigid (complete withdrawal) or porous (emotional collapse).
The key insight is that the duration and pattern of stress matter more than intensity. A person who experiences ongoing relational or occupational stress may show immune suppression and elevated inflammatory markers years after the initial exposure, indicating that the system “remembers” emotional strain as physiological threat (Slavich, 2020).
Beyond Self/Non-Self: Microbiome & Circadian Boundaries
Some of the most cutting-edge work expands the idea of boundaries beyond the mind and immune system altogether, exploring how the microbiome and circadian rhythms regulate stress adaptation. Chronic stress alters gut microbiota diversity, which in turn modulates immune signalling, mood, and cognitive performance (Foster et al., 2023). Similarly, circadian disruption—such as inconsistent sleep or late-night work—can impair immune surveillance and emotional regulation, weakening both physical and psychological boundaries (Thaiss et al., 2016).
These findings suggest that emotional boundary repair is not purely intrapsychic—it’s ecological. It depends on sleep, diet, movement, and microbial health as much as therapy or mindfulness.
Toward a Biology of Boundaries
The convergence of these discoveries points to a radical idea: the boundary between self and world is a living system. Interventions that restore immune rhythm—through anti-inflammatory nutrition, meditation, somatic therapy, and stable daily cycles—may strengthen the emotional sense of self as effectively as traditional psychotherapy (Bower & Kuhlman, 2023; Davidson et al., 2003; Creswell et al., 2012).
As our understanding deepens, we may begin to assess boundary health not only through emotional awareness, but through measurable biomarkers—patterns of inflammation, cortisol rhythm, or microbiome stability. The science is beginning to confirm what human experience has always known: the body’s defences and the self’s defences rise and fall together.
If stress has shaped your story more than you’d like, perhaps it’s time to look at it differently.
Book a call with me to explore how biology, psychology, and narrative intersect in your own drive.
