what your nervous system hears
why your body stays on alert long after the danger has passed
In the last two posts, we talked about what trauma really is and how the body holds onto what the mind tries to forget. Today I want to talk about the system that does a lot of that holding: the nervous system. Once you understand how it works, so much of what you feel in your body starts to make sense.
Your nervous system is your body's communication network. It connects your brain to every part of you, constantly sending messages back and forth. Part of it you control, like deciding to lift your arm or take a step.
But a big part of it runs entirely on its own, beneath your awareness. That part is called the autonomic nervous system, and it's in charge of all the things you never have to think about: your heartbeat, your breathing, your digestion, your blood pressure, your body temperature. It keeps you alive without asking for your input.
The autonomic nervous system has two main branches, and they work a bit like the gas pedal and the brakes in a car.
The sympathetic nervous system is the gas pedal. It's what kicks in when your body senses danger, and it's often called the fight or flight response. Your heart rate speeds up, your breath gets quick and shallow, your muscles tense, and stress hormones like adrenaline and cortisol flood your system. Blood moves away from things like digestion and toward your arms and legs so you can run or defend yourself. In a truly dangerous moment, this response is a gift. It's what gets you out of the way of a speeding car.
The parasympathetic nervous system is the brakes. It's often called rest and digest. When it's in charge, your heart rate slows, your breath deepens, your muscles soften, and your body turns its attention back to healing, digesting, sleeping, and restoring. Much of this work happens through the vagus nerve, a long nerve that wanders from the brainstem down through the throat, heart, lungs, and belly. This is the state where we feel calm, open, and connected to the people around us.
There's also a third response worth knowing about. When a threat feels too big to fight or escape, the body can move into freeze or shutdown. Everything slows down. We go numb, foggy, or far away. It's the body's way of protecting us when there's nowhere to go, and many people who have lived through overwhelming experiences know this state well, even if they've never had a name for it.
In a healthy rhythm, the body moves between these states all day long. Something stressful happens, the gas pedal engages, and once it passes, the brakes kick in and we settle again. Some people call the range where we can handle life's ups and downs and still feel like ourselves the window of tolerance. Inside that window, we can feel stress without being swept away by it.
Trauma changes this rhythm. When we've lived through something overwhelming, or through years of stress without enough time to recover, the nervous system can get stuck. The window of tolerance gets smaller. It doesn't take much to push us out of it, and it takes a lot longer to come back.
For some people, the gas pedal gets stuck down. The body stays on high alert, constantly scanning for danger even when we're safe. This can look like anxiety, racing thoughts, irritability, trouble sleeping, a jumpy startle response, or never quite being able to relax. For others, the body leans into shutdown. This can look like exhaustion, numbness, depression, feeling disconnected from yourself or others, or just going through the motions. Many people swing back and forth between the two.
And because the nervous system runs so much of the body, the effects don't stop at our moods. When stress hormones stay elevated for long periods, it can affect digestion, sleep, immune function, muscle tension, and inflammation. This is part of why so many people carrying unresolved stress and trauma also live with headaches, stomach issues, chronic pain, or a body that just never feels rested.
Here is the most important thing I want you to take from this: none of this means you are broken. Your nervous system learned these patterns to keep you safe. It did its job. It's just still doing it long after the danger has passed. And the beautiful thing is that the nervous system can learn again. With patience, practice, and support, it can begin to feel safe, and the window can slowly widen.
One small way to begin is simply through your breath. Try breathing in gently through your nose, and then letting your exhale be a little longer than your inhale. Longer, slower exhales are one of the simplest ways to signal to your body that it's okay to settle. Do this for a few rounds and notice what shifts, even if it's something small.
In the next post, I'll share more practices for supporting and regulating your nervous system, simple ways to come back into your body and back into that place of safety. For now, I'd invite you to sit with this: when life gets hard, where does your body tend to go? Does it speed up, or does it shut down?
Your body has been working so hard to protect you. It deserves to know it can rest now.
