When Your Body Speaks: the Nervous System 101

Have you always wondered what the nervous system really is? Join me as I break down its functions, its role in the body, and how it applies to your mental health.

When Your Body Speaks: the Nervous System 101

If you’d like to learn more about the window of tolerance and its positive effect on understanding ADHD, check out this connected article: Open Window, Open Mind: ADHD and Understanding Your Window of Tolerance.

In this article, I’ll break down what the nervous system is, its role in your body, and how it applies to your mental health.

If you’re anything like me, hearing the words “nervous system” sounds daunting, overly scientific, and flashes you back to grade 10 science. But fear not! I’ve sat through the lectures so you don’t have to. Let’s break it down together and get a better sense of what it means, and why it matters to our mental health.

Have you ever noticed your heart racing before a big presentation, job interview, or on a busy highway; feeling like it was going to beat out of your chest? Or how about feeling calm in the presence of someone you trust, being content to sit in silence and be totally relaxed?

That’s your nervous system at work!

I know it can feel silly trying to “listen to your body,” but humour me and give it a try. Slow down, steady your breathing, close your eyes if it feels right. Now:

• What do you notice?
• What do you feel?
• What is your body saying it needs right now?

These small moments of check-ins with your body give your nervous system a chance to finally be heard.

What Is the Nervous System?

Let’s think of it as your body’s own, personalized “communication network” that shapes how you react to, feel about, and connect with the environment around you. It’s a vast system made up of nerves, the spinal cord, and your brain.

Nerves are like sensors all over your body that receive input from the world: “this pan in my hand is hot,” “my lungs need more air,” or “gosh that cute dog is big and running straight at me.” These inputs are sent as electrical and chemical signals to the spinal cord, which transports them all the way to the brain where they’re interpreted and a split-second decision is made on how to react. Then a new signal is sent from the brain back along the network to the appropriate body part. *sound of a pan clattering to the floor*

Think of your nervous system like a “command centre” that is controlling your life—your nervous system is responsible for making sure you breathe, swallow, blink; you name it! No occurrence too small, the nervous system is responsible for it all.

A Brief Aside | Some Fancy Terms

We’re going to need a few more terms to explain how your nervous system affects your mental health. Despite their fancy medical names, they’re all part of the system I just described:

• Central nervous system (CNS): brain and spinal cord; the main command centre.
• Peripheral nervous system (PNS): all the nerves; the messengers sending signals to the CNS.
• Autonomic nervous system (ANS): the automatic system that controls all your involuntary body functions like breathing, heart rate, and digestion. (It’s made up of the next two systems: para- and sympathetic nervous systems.)
  • Sympathetic nervous system: this is your fight-or-flight response that helps prepare your body for intense physical activity in response to stress or danger.
  • Parasympathetic nervous system: this is your rest-and-digest response that promotes relaxation, conserves energy, and regulates essential functions like digestion and heart rate when you are calm and safe.

I know that’s a lot, but don’t worry, there won’t be a test!

The Nervous System in Mental Health

Your nervous system, the command centre, is the filter that decides whether you feel safe or threatened, connected or shut down. When your nervous system is regulated, your mind has room to think clearly, feel deeply, and connect authentically. But when it’s stuck in survival mode, even the best coping strategies can feel impossible. In other words: your nervous system sets the stage for your mental health because it is the foundation that everything else rests on.

To understand that foundation, we need to talk about the functions of your autonomic nervous system (the sympathetic and parasympathetic); specifically, your fight-or-flight and rest-and-digest responses. Both are equally important for helping you regulate your nervous system back into what’s called your “window of tolerance.”

Remember that presentation I asked you about earlier, when your heart felt like it would beat out of your chest? That is your sympathetic nervous system communicating with you! It’s preparing you for action when stimulus in your environment says, “Danger!” (Even if “danger” just means giving an important presentation.)

Now, how about that person you feel incredibly relaxed around like they have a calming energy that makes your heart rate slow down? This is your parasympathetic nervous system communicating with you, saying you’re safe so you can relax and conserve energy for the next time you experience “danger.”

Does it make a little more sense now why you get so nervous before exams and feel like you’re going to hurl everywhere? Or why you might have a hard time feeling comfortable in unfamiliar environments? It’s your autonomic nervous system communicating with you, telling you how it feels. You just need to slow down and be brave enough to listen.

What Safe Means to You

Nervous systems are like blueprints for the lives we’ve lived and the experiences we’ve had. No two nervous systems have experienced the exact same set of lived experiences, which means everyone’s command centres have developed unique responses to different stimuli in the world. What regulates you, might dysregulate me!

But the coolest part about our nervous system is: they are always working to keep us totally and completely safe. Sure, sometimes they misfire or misread potential threats; but the intention is always safety. What we can work on in therapy is redefining what safe means to you.

Learning about your unique nervous system and how it responds in situations can be liberating, leading you to improving your regulation and self-soothing skills—and your self-compassion! So the next time you notice your breath quicken or your shoulders tense, slow down and ask: what is my nervous system trying to tell me?

And if you can’t figure out what your nervous system is saying, maybe a therapist can help. We’ll start by understanding your nervous system—then we work on befriending it! 🧠💛