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Defense Mode The Biological Basis For Defense Mode (Understanding The Vagus Nerve)

The AE Team

The AE Team

4 min read
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Do you feel that? Right there in your chest. . . Listen. . .

That’s your heart. That’s what’s keeping you alive right now.

If you’re like most people, your heart will have beat roughly 4,800 times in the last hour (80 times per minute). However, what you may not realize is that not all of those beats were exactly the same. Most people’s heartbeat tends to be pretty steady but not perfectly so. Some beats happen a little faster and therefore closer together. Others are just a little slower and farther apart. That variation between your heartbeats has a special (though not very original) term: Heart Rate Variability.

A little ways behind your heart is your spine, which supports your neck and head and runs down to your tailbone. Do you feel it there? Strong and steady, it’s got your back (pun intended). Running along and through your spine are a lot of different nerves, all of them important. However, for today, we’re going to focus on just one them: the vagus nerve (pronounced like Las Vegas, but spelled differently). It plays a role in a lot of critical functions, a couple of which are controlling your heart rate and the regulation of the stress response (fight, flight, or freeze). Basically, the vagus nerve’s job is to keep your heart rate steady, calm you down, and then keep you calm.

The Vagus Nerve

Because of the vagus nerve’s direct connection to the heartbeat, there’s this handy method of measuring how well it’s doing its job: measuring your heart rate variability (HRV). If your HRV is more adaptable– meaning there is a greater variation in time between each heartbeat (high variability)-- then that is an indication that your vagus nerve is functioning effectively. You have what’s called high vagal tone, and chances are excellent that you handle stress more effectively. You probably tend to feel less anxiety, and in general, it’s easier for you to regulate and deal with negative emotions. You’re cool as a cucumber. When stressful situations arise, you’re able to take things as they come, and let the stress roll off you, like water off a duck’s back. High vagal tone is a sign of emotional resilience.

On the flipside, we have those with low vagal tone. Here you have an HRV that is less adaptable and exhibits lower levels of variation. While stress is an inevitable part of life, individuals with low vagal tone are more reactive to that stress. It is harder for them to deal with difficult situations and negative emotions as they arise. They might experience more emotional turbulence and feel overwhelmed as they navigate the inevitable ups and downs. Low vagal tone is often seen in individuals with PTSD (Post Traumatic Stress Disorder).

So who cares? Why I am I boring you with all this science stuff? Good question.

Here’s the bottom line: low vagal tone = Defense Mode. They go hand-in-hand. Defense Mode is a state in which someone with Asperger’s is scared, frustrated, or angry, as well as shut down and withdrawn. On the behavioral level, Defense Mode typically manifests as some variation of fight, flight, or freeze.

Low vagal tone is a state in which someone is naturally more susceptible to stress and negative emotion, and therefore more likely to react with fear and anger. They’re more likely to lash out, run, or shut down. Fight, flight or freeze.

This matters because I want you to understand that that there is a real, biological basis for why your Asperger’s child is in Defense Mode and has fewer spoons than you. You can literally measure it with an ECG (electrocardiogram).

When your child is in Defense Mode, they will naturally have fewer spoons because they’ll lose them more quickly. A stressor that feels imperceptibly minor to you might feel enormous to them. Even positive emotions, like excitement, can feel overwhelming to your child and can be draining in their own way. Your child’s vagus nerve is not functioning at full capacity, and therefore they are not physically capable of regulating their emotions and stress response the same way you do. They are often a lot closer to their breaking point and can become overwhelmed more quickly.

Please recognize that this not some sort of moral failing on their part. We don’t yet fully understand why trauma (like being in a warzone), or the innate neurological differences of Autism (such as sensory issues) cause damage and inflammation to one’s vagus nerve, but we know it happens. More importantly, we know that there is a real, biological basis for Defense Mode, overwhelm & shutdown, and that science can now prove that people on the spectrum aren't just being "lazy".

Note: This is an excerpt from our book "7 Easy Ways To Motivate Someone With Asperger's". Get the whole book here.

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