The Nervous System and Chiropractic: What You Need to Know Part 4: Rest vs. Stress – Subluxations and the Autonomic Nervous System
Welcome back to our series, The Nervous System and Chiropractic: What You Need to Know. So far, we’ve explored what subluxations are, how they interfere with brain-body communication (Part 1), and how they impact both your motion sensors (mechanoreceptors) and your alarm system (nociceptors) (Parts 2 and 3). Together, we’ve seen how these imbalances can create miscommunication in the nervous system—even before symptoms show up.
In this installment, we’re taking a closer look at how subluxations affect your autonomic nervous system (ANS)—the part of your nervous system that runs in the background, controlling vital functions like digestion, heart rate, breathing, and immune activity. Subluxations don’t just affect movement and pain—they can also shift the balance of your ANS, often without you realizing it.
Part 4: Rest vs. Stress – Subluxations and the Autonomic Nervous System
The Autonomic Nervous System: Two Sides of the Same Coin
Your autonomic nervous system (ANS) controls almost everything in your body automatically—your heart rate, digestion, breathing, blood pressure, and even how your organs work—without you having to think about it. It has two main branches that work together to keep you alive, healthy, and adaptable:
Sympathetic nervous system (SNS):
This is your body’s fight-or-flight system. It kicks in when you face stress or danger, whether that’s a real threat, like narrowly avoiding a car accident, or a perceived one, like rushing to meet a deadline. The SNS speeds up your heart, raises blood pressure, slows digestion, and tenses your muscles so you’re ready to react quickly.
Parasympathetic nervous system (PNS):
This is your rest-and-digest system. It activates when stress has passed, helping your body slow down, recover, digest food, repair tissues, and store energy. The PNS also plays a key role in homeostasis, which is your body’s way of keeping internal conditions stable and balanced—like temperature, blood pressure, and energy levels—so all your systems work together smoothly. This is the system that allows you to relax, sleep well, and feel restored after a busy day.
When your nervous system is balanced, your body can switch smoothly between these two states depending on what’s needed. For example, the sympathetic system leads when you’re exercising, running late, or lifting something heavy, while the parasympathetic system takes over when you’re resting, eating, or sleeping.
But when your spine is out of alignment—a condition chiropractors call a subluxation—this balance can shift too far toward stress mode. Over time, this can trap your body in what’s called sympathetic dominance, where you’re stuck in fight-or-flight even when there’s no real danger, leaving your body tense, tired, and less able to heal and recover naturally.
How Subluxations Flip the Switch Into Stress Mode
A subluxation isn’t just a stiff or sore joint. It changes the way your nervous system receives information from your spine. Here’s how that process unfolds:
1. Joint restriction develops
A spinal joint becomes restricted or misaligned—often from stress, poor posture, or injury—and loses its normal motion.
2. Reduced mechanoreceptor input
When the joint stops moving correctly, the mechanoreceptors (tiny motion sensors in your spine) send less information to your brain about healthy movement and position. These sensors normally tell your brain that everything’s working fine. When their signals drop, your brain gets less of that “everything’s okay” message.
3. Increased nociceptor input
At the same time, nearby tissues may become irritated. This activates nociceptors, the body’s built-in alarm sensors, which send more “something’s wrong” signals to the brain. So while your motion sensors are quieting down, your alarm sensors are getting louder, flooding your nervous system with warning messages.
4. Imbalanced brain signals
Your brain now receives fewer “safe, normal” messages and more “danger, protect” messages. This imbalance is called dysafferentation, and it can make your brain interpret ordinary body signals as potential threats.
5. Sympathetic system activation
Because your brain’s main job is to keep you alive, it reacts to this imbalance by switching into survival mode. Even when there’s no real life-threatening danger, the sympathetic nervous system can activate, putting your body into fight-or-flight mode as if it were facing a true threat.
6. Fight-or-flight takes over
Once fight-or-flight kicks in, your heart rate increases, digestion slows down, and your muscles stay tense. The deeper spinal stabilizer muscles can even get “turned off” because your brain prioritizes bigger muscles that help you move quickly and protect yourself. This leaves your spine less supported and more vulnerable to future restrictions or injury.
7. Sympathetic dominance develops
When this pattern continues for weeks or months, your body gets stuck in high alert. The deep spinal muscles that normally keep each vertebra stable can shut down, leaving the bigger, outer muscles to work harder and maintain protection. Without the deep muscles providing accurate feedback, your brain loses some sense of where your spine is in space (proprioception), which perpetuates the sympathetic, fight-or-flight response.
As a result, it becomes harder for the parasympathetic, rest-and-digest system to take over. Chronic joint restriction and faulty nerve signals reinforce this loop, keeping your body in stress mode long after the original cause has passed.
This response isn’t random—it’s your brain doing exactly what it’s designed to do. When communication between your spine and brain is disrupted, your brain senses that something isn’t right and treats it as a potential threat. Just like spotting a tiger, your body goes into protection mode until the danger is resolved. That’s how seriously your brain treats a subluxation.
How Sympathetic Overdrive Shows Up in the Body
When your body stays in stress mode too long, it doesn’t just cause tension in your spine—it affects nearly every system in your body.
Digestive System
When your body is stuck in stress mode, digestion doesn’t work the way it’s supposed to. Blood is pulled away from your stomach and intestines and redirected to your muscles and heart to prepare for immediate action, which slows the digestive process. Food moves more slowly through your system, making it harder to absorb important vitamins, minerals, and other nutrients. Over time, this can leave your brain, muscles, and organs with less energy and make you feel tired or mentally foggy. Stress hormones can also upset the balance of stomach acid, which may lead to acid reflux or heartburn, while the heightened nervous system activity can make your stomach feel tense or fluttery—a “nervous stomach.” Chronic stress and poor digestion can weaken gut health, which plays a role in your immune system, leaving you more prone to inflammation or infections. On top of all this, stress can change your appetite, either suppressing it or causing cravings, further affecting nutrient intake and energy levels. Altogether, these effects make it harder for your body to function and recover efficiently.
Cardiovascular System
Stress speeds up your heart rate and raises your blood pressure to help you react quickly. But when this happens constantly, it puts extra strain on your heart and blood vessels, wearing them down faster.
Immune System
When your body is in fight-or-flight mode, it releases stress hormones like adrenaline and cortisol. These hormones help you react quickly in dangerous situations, but they also slow down immune function because your body prioritizes survival over healing. Chronic sympathetic dominance can weaken your immune system, making you more likely to get sick, heal more slowly, or experience inflammation more easily.
The gut plays a major role in your immunity, and stress can disrupt gut health in several ways. High stress hormones can alter the balance of bacteria in your digestive tract, reducing beneficial microbes and allowing harmful bacteria to thrive. This imbalance, called dysbiosis, can increase inflammation, impair digestion, and further weaken your immune system. Together, these effects make it harder for your body to fight infections, repair tissues, and maintain overall health when stress is constant.
Muscles and Joints
When a joint is stuck or restricted, the deep stabilizing muscles of the spine, like the multifidus and rotatores, can get “turned off.” At the same time, the larger outer muscles, like the erector spinae, tighten to protect the area. When the deep muscles shut down, your brain loses some of its sense of where your spine is in space—this is called reduced proprioception. Without accurate feedback from these small stabilizer muscles, the nervous system can stay in sympathetic, fight-or-flight mode longer than necessary. This protective pattern keeps muscles tense, burns extra energy, and limits normal movement. Over time, it can cause stiffness, soreness, tension headaches, and a higher chance of re-injury because the fine control provided by the deep stabilizers is missing.
Sleep and Energy
A body stuck in stress mode struggles to fully relax. When stress hormones like cortisol and adrenaline stay high, your brain and body stay on alert instead of winding down for rest. Cortisol can keep your mind racing at night, while adrenaline raises your heart rate and makes it hard to get into deep, restorative sleep. Even if you do fall asleep, you may wake up easily or feel restless. Poor digestion and nutrient absorption can add to the fatigue, leaving you tired and drained during the day.
Emotions and Mood
Long-term stress keeps stress hormones high and lowers the brain chemicals that help you feel calm and happy. This can lead to anxiety, irritability, or emotional ups and downs. When your body isn’t getting proper rest or nourishment, these feelings can intensify.
Chronic sympathetic dominance also affects the hypothalamus, the part of your brain that helps control sleep, hunger, body temperature, and hormone balance. When the fight-or-flight system stays active, the hypothalamus keeps signaling your body to release stress hormones like cortisol and adrenaline. Over time, this constant activation can throw off your natural sleep cycles, appetite, and even reproductive and thyroid hormones. That’s why people under chronic stress often feel wired but tired, crave comfort foods, or notice changes in their energy, mood, or hormones.
Thinking and Focus
When your body is stuck in fight-or-flight mode, your brain shifts into survival gear. The part of your brain that helps you think clearly and make good decisions—the prefrontal cortex—starts to slow down. Instead, your brain puts more energy into the amygdala, the area that looks for danger and keeps you alert. This makes sense if you’re in real danger, like trying to avoid a car accident. But if your body stays in that state for too long, it becomes hard to concentrate, plan ahead, or stay calm.
Over time, this constant stress can lead to brain fog, forgetfulness, and trouble focusing. You might feel scattered, unmotivated, or easily overwhelmed because your brain is spending more time reacting than thinking.
Chronic sympathetic dominance also affects the hippocampus, which helps with learning and memory. When stress hormones like cortisol stay elevated for too long, they can shrink or weaken cells in this part of the brain. That means your ability to store new information or recall details from the past can suffer, making you feel forgetful or mentally foggy.
Overall Adaptability and Resilience
When your body is stuck in sympathetic dominance, it becomes harder to handle new challenges or changes in your environment. Your muscles and joints stay tense, and your nervous system is constantly on high alert, making it difficult for your body to relax and respond appropriately.
Even small changes—like a noisy room, a shift in temperature, a sudden schedule change, or minor physical stress—can feel overwhelming. Your body reacts as if these everyday events are serious threats, overusing energy and keeping stress hormones elevated. Over time, this constant state of alertness reduces your flexibility, both physically and mentally, making it harder to recover, adjust, and respond calmly to new situations.
Because your body is so focused on survival, systems that normally help you adapt—like digestion, immunity, sleep, and hormone balance—don’t function optimally. This means you have less energy, slower recovery, and a harder time coping with environmental changes, whether they’re physical, emotional, or social.
Restoring balance in your nervous system allows your body and mind to become more flexible again, improving your ability to respond to stress, recover from challenges, and adapt smoothly to whatever life throws at you.
Your Body Wasn’t Meant to Live in Fight-or-Flight
The fight-or-flight response is a powerful and lifesaving tool. It helps you slam on the brakes to avoid a car accident or jump out of the way of danger. In those moments, your body makes lightning-fast changes—your heart races, your breathing quickens, and blood rushes to your muscles.
But here’s the key point: this response was meant to be temporary. Once the danger passes, your body should shift back into rest-and-digest mode so it can repair and recharge. Your body was designed to live mostly in parasympathetic drive, with only short bursts of sympathetic activity when necessary.
Imagine if a fire alarm went off constantly instead of only during a fire—it would be exhausting and stressful. That’s exactly what happens when your nervous system gets stuck in fight-or-flight.
When that happens, your heart, gut, immune system, and brain all feel the strain. You may notice fatigue, poor sleep, digestive problems, or frequent illness—not because your body is weak, but because it’s being asked to live in a state it was never designed to stay in.
Your body thrives in balance. Short bursts of stress are normal, but long-term survival mode wears you down. That’s why restoring balance through chiropractic adjustments is so important—it helps your body return to the calm, healing state it was built for.
How Chiropractic Adjustments Restore Balance
Chiropractic care focuses on correcting subluxations—those restricted or misaligned spinal joints that interfere with your body’s communication network. By restoring normal motion and alignment, adjustments help your nervous system rebalance and your body function more efficiently.
Reactivating Mechanoreceptors
Adjustments restore healthy joint motion, which “wakes up” the mechanoreceptors (the motion sensors). These sensors then send clear signals to the brain that movement is normal and safe, helping reduce muscle guarding and tension.
Calming Nociceptors
When a chiropractor adjusts the joint, it reduces irritation in the surrounding tissues. This quiets the nociceptors—the alarm sensors—so your brain no longer feels the need to stay in constant fight-or-flight mode.
Balancing the Autonomic Nervous System
As the motion sensors send healthy information again and the alarm sensors calm down, your nervous system shifts out of sympathetic dominance. This allows your parasympathetic system to come back online, supporting rest, digestion, repair, and immune strength.
Improving Whole-Body Function and Adaptability
Better motion and communication between your body and brain improve overall coordination, flexibility, and recovery. You may find that you not only move better but also sleep deeper, digest food more easily, and handle stress with greater resilience.
Prevention and Early Intervention
Chiropractors also focus on catching and correcting subluxations before symptoms appear. Regular care helps your body maintain balance and prevent the long-term effects of stress on your nervous system and overall health.
The Big Picture
Subluxations don’t just affect how your spine moves—they affect how your entire nervous system communicates. When a spinal joint is restricted, motion sensors send less healthy input, alarm sensors send more distress signals, and your body can get stuck in stress mode.
This imbalance can show up as digestive problems, poor sleep, muscle tension, mood changes, and reduced adaptability. Chiropractic adjustments help correct those joint restrictions, reactivate normal communication, and bring your nervous system back into balance.
When your body is back in that balanced state, it can rest, heal, and respond to life’s challenges the way it was designed to.
In the next part of this series, we’ll explore central sensitization—what happens when your nervous system stays on high alert for too long. You’ll learn how that contributes to chronic pain, fatigue, and brain fog, and how chiropractic care can help “reset” your nervous system and restore calm.
At Wellness Within Chiropractic, we proudly serve Hoschton, Braselton, and all of Jackson County, GA with natural, holistic chiropractic care. Dr. Carrillo and our team are dedicated to helping you move better, feel stronger, and support your long-term wellness. If you’re searching for a trusted chiropractor near you, schedule an appointment today and discover the benefits of chiropractic care for your health and lifestyle.