3 Nov 2026
When Your Body Thinks You're in Danger: The Biology of Safety, Threat and Ageing
What happens when your body behaves as though you're under threat — even when there's no obvious danger?
In this episode of the Biohackher Podcast, I'm joined by Dr Olivia Lesslar for a fascinating conversation about psychoneuroimmunology, or PNI, and the constant communication taking place between our brain, nervous system, immune system and endocrine system.
We explore how the body interprets threat, why the same situation can trigger completely different physiological responses in different people, and what can happen when acute stress becomes a chronic state of vigilance.
Olivia explains why the autonomic nervous system plays such an important role in determining whether the body directs its resources towards survival or towards repair, regeneration and recovery. We also unpack the difference between feeling safe and feeling secure, and why resilience isn't necessarily about avoiding stress, but developing the capacity to respond to it more effectively.
We delve into Olivia's Nine Ancient Survival Threats framework and how modern-day experiences may activate biological pathways that originally evolved to help us survive very different environments.
We also discuss safety signalling: the physical, psychological and environmental cues that may help the body interpret its surroundings as less threatening. From social connection and time in nature to sleep, adequate nutrition, self-compassion and simply having a sense of agency, many of the signals Olivia believes matter most are surprisingly accessible.
Later in the conversation, we explore the emerging role of mitochondria beyond energy production, including their involvement in cellular signalling and stress responses. Olivia also introduces her developing "Three Cs" framework — charge, coherence and capacity — as a way of thinking about why some people tolerate interventions easily while others can struggle with even very small changes.
Finally, we bring it back to longevity. If healthy ageing depends in part on our ability to repair, adapt and recover, could our ability to appropriately interpret safety and threat be another piece of the longevity puzzle?
In this episode, we discuss:
What psychoneuroimmunology actually means and why the brain, immune, endocrine and nervous systems cannot be viewed in isolation
How psychological, emotional, social and physical stressors can activate overlapping biological pathways
Why threat is subjective and two people can respond very differently to the same event
The role of the sympathetic and parasympathetic nervous systems in resource allocation
Why Olivia distinguishes between being safe and feeling secure
How chronic stress can change the way the body allocates resources
The concept of "requisite variety" and why having more tools and experiences may improve resilience
Why co-regulation and social connection can be powerful biological signals
Olivia's Nine Ancient Survival Threats framework
What safety signalling means and why it is highly individual
Why chronic illness should never be dismissed as being "all in the mind"
Whether the nervous system can relearn safety after years of hypervigilance
How placebo, nocebo and predictive processing fit into the conversation
Why mitochondria are increasingly being viewed as signalling and sensing organelles, not simply energy producers
The cell danger response and what it may tell us about chronic illness and recovery
Olivia's Three Cs: charge, coherence and capacity
Why lifestyle choices remain some of the most powerful tools available to us
The relationship between chronic stress, inflammation, cellular repair and healthy ageing
Practical ways to create more signals of safety without expensive biohacking technology
Key moments
02:00 – What is psychoneuroimmunology?
03:10 – What happens biologically when the body interprets something as a threat?
06:10 – Why threat is subjective
08:30 – Psychological versus physical stress
11:30 – Co-regulation, social connection and longevity
12:40 – Survival versus repair: how the body allocates resources
17:40 – What happens when the threat-detection system gets it wrong?
20:30 – Requisite variety and building resilience
22:20 – Can we train ourselves to respond differently to stress?
27:00 – Olivia's Nine Ancient Survival Threats
31:20 – What is safety signalling?
35:15 – Chronic illness and difficulty sustaining a parasympathetic state
39:20 – Can the nervous system relearn safety?
42:30 – Why chronic illness is not simply "in your head"
49:30 – Mitochondria, cellular signalling and the cell danger response
54:30 – The Three Cs: charge, coherence and capacity
59:10 – Why lifestyle choices matter
1:01:10 – Stress, inflammation and biological ageing
1:04:10 – Should safety and threat perception be part of the longevity conversation?
1:07:20 – Practical ways to send the body more signals of safety
One idea to take away
Healthy ageing may not only be about what we eat, how we exercise or which supplements we take. It may also involve how effectively our system can assess its environment, respond to stress and then return to a state where repair and recovery can take place.
As Olivia puts it throughout this conversation, there is enormous value in curiosity, self-compassion and working with the body rather than constantly trying to override it.
CONNECT WITH DR OLIVIA LESSLAR
Instagram: https://www.instagram.com/drolivialesslar
LinkedIn: https://www.linkedin.com/in/drolivialesslar
Website: https://www.drolivialesslar.com
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