Your Autonomic Nervous System apprenticeship starts here.

Veterans, children who have experienced abuse or neglect, and others who have suffered single event trauma are often left with emotional and psychological scars. Despite decades of effort, there are no clear-cut answers about how to heal them.
Pills, talk therapy, and support groups help some people but not others. Some researchers believe trauma can leave an emotional imprint, not just in our psyche, but in the tissues of our body via the nervous system (van der Kolk, 2015; Levine, 2015).
The picture you have in your mind of the nervous system probably includes the brain, spinal cord, and a truck loads of nerves that convey messages between the body and brain. This may be an oversimplification, but essentially correct. What many people don’t know is the is divided into two major regions: the central and peripheral nervous systems. The central nervous system (CNS) is the brain and spinal cord, and the peripheral nervous system (PNS) is everything else. It is so named because it is on the periphery—meaning beyond the brain and spinal cord.
The PNS can be further divided into two parts mostly based on a functional difference in responses. The somatic nervous system (SNS) is responsible for voluntary movements (that is, it kicks in when you want to go for a jog), while the autonomic nervous system (ANS) acts as a control system and most functions occur without conscious thought (for example, your reaction when someone jumps out from behind a corner and yells “boo!”). This is the system we are interested in.

What is the role of the autonomic nervous system?
The ANS modulates beating of the heart, blinking of eyelids, breath rate and depth, constriction and dilation of blood vessels, detoxification of liver and kidneys, digestion, opening and closing sweat glands, producing saliva and tears, pupil dilation and constriction, urination and sexual arousal . While most of its actions are involuntary, some, such as breathing, work in tandem with the conscious mind. The ANS is classically divided into two subsystems: the parasympathetic nervous system (PSNS) and sympathetic nervous system (SNS).
Broadly, the parasympathetic system is responsible for stimulation of “rest-and-digest” activities that occur when the body is at rest, including sexual arousal, salivation, lacrimation (tears), urination, digestion, and defecation. The sympathetic nervous system is responsible for stimulating activities associated with the “fight-or-flight” response: mobilizing the systems of the body for escape or attacking sources of danger. In truth, the functions of both the parasympathetic and sympathetic nervous systems are not so straightforward, but this division is a useful rule of thumb.

A handy visual
Our brains and physical systems function best when we operate in what Dan Siegel (2010) calls our “window of tolerance.” Pat Ogden (2015) describes it as the “optimal arousal zone.” Janina Fisher (2017) explains it as the zone in which a child can “think and feel at the same time.” The concept suggests that when we are in the window of tolerance we experience ebb and flow (“activation” followed by “rest and digest”). The outcome is that we are better equipped to listen to others, interact cooperatively and learn.
It looks like this…

ANS “ebb and flow” (adapted from Siegel, 2010 and Ogden, 2015)

When stressors appear, we may move close to the edges of the window but are generally able to bring in resources to shift out of what Fisher calls “stickiness.” Note: If you are wondering what stickiness feels like, at the subtlest level, we feel a tightening, a tensing, a sense of closing-down. That feeling has the power to hook us into emotions which lead to words and actions that we have no control over.
When we experience adversity through trauma and unmet attachment needs this can drastically disrupt our nervous system. Our senses are heightened, and our reactions are intensified as resources are less readily accessible.  Adverse experiences also shrink the window of tolerance meaning we have less capacity to ebb and flow and greater tendency to over- or undershoot the window. Indicators are almost always nonverbal (that means, the caregiver needs to look to the body).
– Some bodily cues suggesting too much arousal and an overshooting of the window or hyperarousal: anxiety, panic, fear, hypervigilance, dilated pupils (to let light in to see better), lack of saliva, butterflies in the stomach, faster heartbeat, tensed muscles (readied for action), agitated movement, trouble finding stillness (often making it difficult to sleep, eat and digest food, and manage our emotions). At the most intensified level this may result in dissociative rage/hostility.
– Some bodily cues suggesting too little arousal and an undershooting of the window or hypoarousal. Collapsed body, exhaustion, depression, numbness, endless stare with pin like pupils, slowed heart rate, blank face, excessive requirement for sleep, reduced appetite, and digestion (metabolism).
It looks like this…

ANS “disruption” (adapted from Siegel, 2015 and Ogden, 2015)

Let’s go back to that infamous word: polyvagal. What does it mean? Simply, many or multiple vagus. The tenth cranial nerve (known as the vagus) wanders far and wide, linking up with several different parts of the face or the body. Hence the use of ‘poly’ (Greek for ‘many’). The nervous system’s two branches come on in response to internal and external conditions.
The sympathetic system is our gas pedal. Deb Dana (2018) tells us we need sympathetic active “on” in the background at all times to keep us alert (primed to move), maintain good flow, and provide oxygen to the main skeletal muscles of the body. If a nervous system is dominated by the sympathetic things look very different. When danger or threat is detected, the middle ear will focus on sound frequencies like low grumbles, growls, equipment noises, making it difficult to pay attention to the vocal frequencies of the human voice. It is one of the reasons children with trauma histories find it difficult to hear what someone else is saying.
The parasympathetic system slows things down. It does this in two ways:
One is a healthy and smart brake – ventral vagal.
The other is a survival brake – dorsal vagal.
The ventral vagal. It comes out of the front of the brainstem and links the muscles of the face and neck, larynx and pharynx (involved in speech), heart and lungs. These parts of the body are involved in social communication and connection. When this part of the nervous system is online or dominating, the face is engaged, eyes are soft, there is variability of expression, talking is possible, and the heart rate slows to a comfortable pace that allows a sense of comfort or ease in connection. Presence is possible. When there is a stressor, the ventral vagal will help us to find resources or be resourceful. It will also lower the heart rate (conserve energy), bring the breathing rate down, and guide us back into connection.
The dorsal vagal. This is a more primitive system to the ventral vagal.  It comes out of the back of the brainstem and links the larynx and pharynx with the heart and the lower organs (including the gut). This the state of babies when they are newborn as survival is paramount. The ventral vagal nerve needs priming and modelling to come on board. In effect, babies “borrow” their primary caregiver’s nerve (whether heathy or not) so they can learn to engage with others. The dorsal vagal remains responsible for our day-to-day survival functions (tissue repair, immune system response, protect the gut, “rest and digest”) and may kick in after a stressor to bring us back to calm.
In cases of extreme stress (or when sympathetic system fails), dorsal vagal will take us into survival mode. When this shutdown state is dominating, the parts of the body involved in social communication and connection go offline because the ventral vagal is off: the face becomes flat, the eyes may appear vacant or empty, talking is not possible or nonsensical. This state is useful for survival, but it is not intended to be on for long periods – think of it like driving a car with using your handbrake on. The amount of wear-and-tear would be significant. Indeed, humans and other mammals that have become dominated by this state as a response to threat or overwhelm often have issues in the parts of the body that are controlled by the dorsal vagal—namely, heart, gastro-intestinal, eating-related issues/disorders.
This is why safety is so important!
It is the “neuroception” of safety supports the ventral vagus to come back online. It also supports the state of low-level (or low tone) dorsal vagal “rest and digest.” What can shift a nervous system from sensing safety to sensing threat can be incredibly subtle. And, as parents and caregivers of children with trauma backgrounds, we often assume bad behaviour when in fact what we are seeing is a nervous system response to danger.

How can we convey safety?
Without the experience of an organizing other, the nervous system is stunned.” Sebern Fisher
Remember how we said the social engagement system comes online after the more primitive survival system? If a child didn’t not receive healthy regulation (attunement and attachment) by an “organising other” it directly impacts how the ventral portion of your child’s nervous system is shaped and determines how he or she handles stressors later in life. Therefore, it is critical that they find ways to get back to the harmony and flow between the branches of the autonomic nervous system. And, if you are a foster or adoptive parent to a child impacted by early trauma you are now the organising other; responsible for being regulated and regulating. That’s a huge responsibility!
So, let’s figure out how to do it.
First, it doesn’t work to just say to your child, “you are safe,” because talking taps into your child’s cognitive/verbal state and the difficulties with regulation comes from a time in his life when he didn’t yet have a cognitive system on. For safety and regulation to come back, parents and caregivers must go into the body.
Polyvagal Theory informs us there are five cranial nerves that join in the search for connection through our eyes, ears, voice, and face and head moments (Porges, 2006).

Moving in and out of eye contact is a regulating action. We use the eyes to sense safety and signal safety. Take a moment to experience the power of eyes:
– Stare: strong, focused, you might feel your eyes moving outward from their sockets
– Look: neutral, less focused, you may feel your eyes settling into the back of their sockets
– Gaze: soft, warm, you can feel your eyes deeply resting in their sockets
Note: Porges tells us that if we are activated or in a state of arousal, neutral faces appear to be angry and threatening, so in this state we will see everything through a lens related to survival. But once we become calm and engaged, we can see neutral as neutral.

Modulating middle ear muscle to distinguish the human voice from other environmental sounds is critical. Porges tells us that the middle ear muscles control what sounds get into the inner ear and then into our brain. If we in safe environments, our middle ear muscles tend to be tense and we may have difficulty hearing background sounds because we’re are able to pick up the higher frequencies of human voice (for example, we tune out the noise of the dishwasher while catching up with friends at home). However, if we are feeling unsafe, the muscles will be loose and low frequency sounds will come to the fore. These sounds are biologically wired into our nervous system to reflect predator: earthquakes or thunder, vacuum cleaners, elevators, ventilation systems in buildings, airplanes, footsteps or traffic, and bass in music.
What this means is that information that reaches the brain is dominated by low frequency sounds and human speech is masked (or lost). Interestingly, understanding speech is dependent on processing the lower frequencies of vowels and the higher frequencies of consonants. Wen middle ear muscles are not functioning properly, the subjective experience is hearing speech without being able to decipher words, especially when consonants are at the end of the word.
Note: If you are a parent or caregiver of a child who experience sleep disturbances, there are many low frequency noises at night; many outwardly harmless, like creaking of floorboards or stairs. 

Voice (prosody)
Prosody is the rhythm, music, frequency and intensity of the voice. It reveals the underlying intent. The tone sends a message that the words do not. Dana tells us that “when you don’t know what to say…use a vocal burst.” These are non-language sounds we use to communicate (“ahhh,” “mmm,” “ooooh”). These are understood across cultures, across species, and with a high degree of accuracy.

Face and head movements
Facial expression, like voice, is crucial! This includes eyelid movement, position of the mouth, and head turning (orientation or gestures). When we are stressed or anxious (the gas pedal is on), without thinking about it, we use our facial muscles. To bring ourselves down, we eat or drink, listen to or play music, and talk to people with whom we feel comfortable. Porges believes parents and caregivers can take advantage of this on a conscious level. If a child is in a state of activation or arousal because her nervous system detects that she is in danger, she can use such voluntary behaviour to engage the calming part of the parasympathetic system.

Ruptures need repair
Neuroception is at work beneath awareness in every moment, shifting states in response to messages our nervous system receives. Small ruptures are common experiences: looking away, checking a phone, being distracted by an internal thought, or experiencing a visceral reaction to something said.
If there is a rupture and you move out of ventral vagal while engaging with your child, it’s important to step away for a few moments, map it (where are you on the autonomic ladder?), track it, then make it ‘explicit’ (for example, “I felt an alarm in response to your voice”). Because if you don’t say you have been triggered, your child’s nervous system will notice it and make meaning of it (and it is likely to be inaccurate). Because trauma survivors are often told what they are seeing is not right or what they are seeing is inaccurate, this process of  “noticing and naming” helps them to understand that what they may have noticed is correct.

Don’t stigmatise states, celebrate them!
It is not uncommon for parents and caregivers to tell children impacted by trauma that they are dysregulated (or outside their window of tolerance). “What’s wrong with you?” “You need to change!” or “Why can’t you be ‘normal’?” But this judgment sends children further into defensive states. “I am a piece of sh*t!” “I don’t deserve love!” or “I’ll show them!”
Porges urges parents and caregivers (and therapists) to realize that troubled children can best be healed if everyone accepts and respects what their bodies have done—instead of stigmatizing them for it. “There is no such thing as a ‘bad’ response; there are only adaptive responses,” he says. “The primary point is that our nervous system is trying to do the right thingand we need to respect what it has done. And when we respect its responses, then we move out of this evaluative state and we become more respectful—and we [can] do a lot of healing.”
“So tell them to celebrate how their body responded–—and see what happens.”


  • Dana, D.A. (2018) The Polyvagal Theory in Therapy: Engaging the Rhythm of Regulation. WW Norton & Company: New York
  • Fisher, J. (2017), Healing the Fragmented Selves of Trauma Survivors. Taylor & Francis: London
  • Ogden, P. (2015). Sensorimotor Psychotherapy: Interventions for Trauma and Attachment. WW Norton & Company: New York
  • Levine, P. (2015) In an Unspoken Voice. North Atlantic Books: Berkeley
  • Ogden, P. (2015). Sensorimotor Psychotherapy: Interventions for Trauma and Attachment. WW Norton & Company: New York
  • Porges, S.W. (2011) The Polyvagal Theory. WW Norton & Company: New York
  • Siegel, D. (2010) Mindsight. Random House: New York
  • Van der Kolk. (2015) The Body Keeps the Score. Penquin Books: London

© Felicia Stewart, 2020