Day 9
The Origins of Stress
How Early Development Shapes Responses
Understanding Early Programming of the Nervous System Through Psychoneuroimmunology (PNI)
Our ability to regulate stress in adulthood is profoundly shaped by early childhood experiences. We touched on this in day 6, looking at the environmental and social factors. Today’s session will expand on this and include biological and psychological factors, completing the bio-psycho-social impact of early childhood experience.
From a psychoneuroimmunology (PNI) perspective, stress is not just a psychological experience, it is a biological process involving the nervous, immune, and endocrine systems, shaping long-term mental, emotional, and physical health (McEwen, 2017).
Today, we explore how early childhood experiences program the nervous system, influencing stress resilience, immune function, and autonomic flexibility in later life. You will also learn Physiological Sigh Breathing, a science-backed breathwork technique that helps override deeply embedded stress patterns, reset the nervous system, and restore balance.
By the end of this session, you’ll:
- Understand how early childhood experiences shape stress responses and nervous system function.
- Learn how attachment, trauma, and chronic stress impact long-term health through the PNI lens.
- Use Physiological Sigh Breathing to reset stress responses in real time.
The Stress Response System: A PNI Perspective
Early life stress alters the function of the hypothalamic-pituitary-adrenal (HPA) axis. This axis is the primary pathway and conduit between external stress factors and internal responses. These responses happen automatically and are built and sustained from childhood into adulthood.
The HPA axis increases ortisol production and leading to lucocorticoid resistance a key marker in psychiatric disorders such as depression and anxiety (Otte et al., 2017). Sustained levations in cortisol impair neuroplasticity, reducing the brain’s ability to dapt and regulate stress effectively (McEwen & Seeman, 1999).
Neural-Immune-Endocrine Mechanisms of Stress Regulation
The stress response is a biological feedback system that involves:
The Nervous System
Interprets threats and activates the stress response.
The Endocrine System
This system controls hormones, it releases hormones like cortisol and adrenaline to mobilise energy.
The Immune System
Releases pro-inflammatory cytokines that, when chronically activated, contribute to neuroinflammation and mood disorders (Miller et al., 2009).
Long-term dysregulation
Associated with increased risk for mental health disorders, cardiovascular disease, and autoimmune conditions (Mondelli et al., 2010).
The Biopsychosocial Model: An Integrated Approach to Health
The biopsychosocial model (Engel, 1977) provides a holistic framework for understanding health and disease by recognising the interconnectedness of biological, psychological, and social factors.
Rather than viewing these domains as separate influences, this model emphasises that internal biological and psychological processes dynamically interact with external social and environmental conditions (Borrell-Carrió et al., 2004).
Biological Factors (Inside – Body)
Genetics, neurophysiology, immune function, and autonomic nervous system regulation.
Psychological Factors (Inside – Mind)
Relationships, culture, socioeconomic conditions, trauma, access to resources, and environmental stressors.
Social/Environmental Factors (Outside – Context)
The more you practice this awareness, the more you will begin to notice in real-time what nervous system state you are in.
Rather than viewing these domains as separate influences, this model emphasises that internal biological and psychological processes dynamically interact with external social and environmental conditions (Borrell-Carrió et al., 2004).
The body and mind continuously adapt to social and environmental conditions, meaning that interventions (like breathwork) must address both internal states and external influences to create lasting change.
WHAT THIS MEANS THROUGH PNI LENS
Chronic Stress Response
SOCIAL (ENVIRONMENTAL) - Outside - Context
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Stress (During Childhood) - Attachment, relationships, culture, socioeconomic conditions, trauma, access to resources, and environmental stressors - lack of safety actual and/or perceived somewhere during developmental lived experience.
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LONG TERM EFFECTS - Poor emotional regulation, difficulty with trust and relationships (Shonkoff et al., 2012)
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BIO/PSYCHO - Inside - Body / Mind - dynamics in response to social/environment.
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Dysregulates the HPA axis, over time increases inflammation.
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Leads to hypervigilance (SNS dominance) or shutdown (DVC dominance).
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LONG-TERM SYMPTOMS - Higher risk of anxiety, depression, PTSD, and autoimmune conditions (Baumeister et al., 2016)
Healthy Stress Response
SOCIAL (ENVIRONEMNTAL) outside of - not separete to
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Healthy safe attachment, safe envrionement, safe relationships, culture, socioeconomic conditions, access to resources, and safe environmental context - grounded safety actual and/or perceived throughout developmental lived experience.
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BIO/PSYCHO - inside of dynamics in response to social/environment
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LONG-TERM EFFECTS - Trust in relationships, safe in the World, Adaptive stress responses, higher emotional intelligence, and long-term health benefits (Porges, 2011)
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Early stress lived experience DOES NOT have to define adult well-being—neuroplasticity allows for re-training stress responses through breathwork and vagal toning.
Science of Physiological Sigh:
A Breathwork Technique for Resetting Stress Responses
Physiological Sigh Breathing is a proven method for rapidly resetting the nervous system. This technique is used instinctively by the body (e.g., in sleep or crying) and has been scientifically validated as a tool for reducing acute stress (Huberman et al., 2021).
Enhances oxygen exchange
Balancing CO2 and O2 levels in the blood (Zaccaro et al., 2018).
Reduces physiological arousal
Shifting from SNS activation to PNS regulation (Shaffer & Ginsberg, 2017).
Systemic Health
Stimulates the vagus nerve, increasing heart rate variability (HRV) and autonomic flexibility (Zaccaro et al. (2018)).
Best used in moments of acute stress or overwhelm to rapidly restore nervous system balance.
Day 9 Breathwork
Physiological Sigh for Stress Reset
A physiological sigh is a deliberate breathing technique based on two quick inhales followed by one extended exhale. This pattern helps reduce excess carbon dioxide, signaling the nervous system to relax
A quick and easy technique designed to restore calm and balance in both body and mind. Drawing upon your body’s innate reflex to inhale quickly twice and then exhale slowly, this pattern helps to naturally reduce excess levels of carbon dioxide in the lungs, promoting a sense of ease throughout the nervous system.
Unlike everyday sighs that often occur involuntarily when we are tired or stressed, the physiological sigh can be practiced deliberately to shift your body into a more relaxed state
During times of heightened stress or anxiety, our breathing tends to become shallow and quick. By practicing a purposeful sigh—two short inhales followed by one extended exhale—you help your lungs fully inflate and then gently expel air. This signals your brain that it’s safe to let go of tension. Scientists have studied how physiological sighs naturally occur during sleep and how they serve as a resetting mechanism for the respiratory system.
During times of anxiety or stress, when you simply don’t have the time for a regular breathwork practice, you can consciously harness this natural process to rapidly change your state and improve overall well-being.
This technique is particularly useful for those with early life stress, as it bypasses habitual stress patterns and restores balance.
Key Takeaways
- PNI explains how early stress affects the nervous, endocrine, and immune systems.
- Chronic stress disrupts HPA axis regulation, increases inflammation, and impacts neuroplasticity.
- The biopsychosocial model highlights how social, psychological, and biological factors interact to shape health outcomes.
- Breathwork techniques such as Physiological Sigh can rapidly reset the nervous system and improve autonomic flexibility.
- Long-term practice of nervous system regulation can rewire outdated stress responses, fostering resilience.
Coming up next
Tomorrow, we explore The Mind-Body Connection, uncovering how chronic stress rewires physiological systems, disrupts neuroimmune balance, and increases vulnerability to long-term health challenges—alongside breathwork strategies for resilience and repair.