The autonomic nervous system (ANS) drives heart rate, inner organ function, vision, and other fundamental, involuntary processes. When balanced, the ANS offers a platform of safety that supports everything we care about: forming relationships, getting deep, restorative sleep, and performing at our best.

Yet with sensational news cycles, habit-forming technologies, and other stressors, the modern world can interfere with the delicate balance of the nervous system. These disruptions can impair our focus, limit our energy levels, and derail our overall health.

This guide explores the parts and functions of the ANS, causes of nervous system dysregulation, and lifestyle principles to help you relieve stress by communicating with your body in a language it understands. 

The purpose of the autonomic nervous system

The body has two major nervous systems. The first is the central nervous system (CNS). Home to the brain and spinal cord, the CNS is our processing center, sending, receiving, and interpreting sensory data. The second is the peripheral nervous system, made up of nerves that carry signals throughout the body [1]. 

The peripheral nervous system has two parts: the autonomic nervous system (ANS) and the somatic nervous system. The somatic nervous system refers to actions we consciously control, such as finger or muscle movements. By contrast, the ANS governs the processes outside our conscious awareness, like heart rate, inner organ regulation, pupil constriction and dilation, and other automatic functions.

The ANS constantly makes fine-tuned adjustments based on internal and environmental signals [1]. Some of these changes might include changing your body temperature when you go outside, raising your heart rate as you begin running, or dilating your pupils when you step into the light. 

Parts of the autonomic nervous system

The ANS resides in three locations in the body. Its central location is in the medulla oblongata, the part of the brain responsible for breathing, heart, and blood vessel function [2]. It is also found in the hypothalamus, the bridge between the nervous and endocrine system, your network of hormones, glands, and organs.

The other parts of the ANS, the sympathetic and parasympathetic branches, are located in the peripheral nerves. These branches serve the same organs but affect them in opposite ways.

The parasympathetic branch: This system controls our “housekeeping” or “rest-and-digest” functions. These processes include sleep, digestion, and various forms of relaxation. The parasympathetic branch gets activated by signals of safety: when we feel calm enough to eat, laugh, or meditate, our heart rate, blood pressure, and other functions slow down [3]. These processes help us conserve energy, equipping us with resources to respond to stressors.

The sympathetic branch: The “fight-or-flight” response is the body’s stress management system. In the presence of a threat, the sympathetic system diverts resources away from any function not important for defeating immediate danger. When activated, the sympathetic branch raises blood pressure, slows digestion, and directs blood flow away from internal organs and in the direction of the skeletal muscles [3].

Emergencies and other demanding situations activate the sympathetic system. Conversely, the parasympathetic brings the body back to a normal, calm state. In the case of a balanced ANS, we move seamlessly between parasympathetic and sympathetic activation—we’re able to respond to a threat when it arises, then recharge our batteries when it passes. 

Sources of nervous system dysregulation

Our stress response can be life-saving in some contexts. But we can become dysregulated if stressors arise chronically. When this occurs, we struggle to transition seamlessly between autonomic states. Although nervous system dysregulation can come from many sources, there are two broad catalysts.

Trauma and the nervous system

Stress psychologists regard trauma as a root cause of nervous system dysregulation. Most people associate trauma with acute danger, but it can also result from more mundane situations. Surgeries and even routine medical procedures can be sources of trauma. Lost jobs or friendships can also be traumatizing [4]. 

In his classic book, Waking the Tiger: Healing Trauma, psychologist Dr. Peter Levine explains that we become traumatized if we don't complete our primitive, pre-programmed biological response to stress [5]. When the stakes are high, we have three options: we can fight, flee, or freeze. In most cases, we either contend directly with the stressor or run from it. In circumstances where these responses aren’t helpful, the body freezes. 

Freezing represents the activation of our primitive immobilization response, which we share with reptiles and other vertebrates. If you’ve encountered a motionless reptile in a pet store, you’ve seen the immobilization response in action. Reptiles require much less energy to function. As a result, they can easily transition from immobilized to mobilized states. Humans respond much differently. 

When we immobilize in response to a threat, the energy the body would have employed in fighting or fleeing gets amplified and fixated in the nervous system [5]. If we don't expend the resources produced by the stress response, they don’t just disappear. Instead, trauma stored in the body can contribute to stress long after a threat passes [6]. 

Because disrupted physiological processes can cause trauma, we need to relieve stress at the emotional and physical levels, (described below).

The autonomic nervous system vs. the modern world

The modern world can be another source of nervous system dysregulation. We're exposed to many novel forms of stress. And it isn’t only because we live in a chaotic social climate. Instead, evolutionary psychologists hypothesize that many of our mental and physical health challenges result from an evolutionary mismatch or a misalignment between the tribal settings of our ancestors and our current landscape [7]. 

Of course, there is no single ancestral lifestyle: our ancestors had many different diets and lived in many environments. Still, the slow process of evolution has not caught up to many of our technologies and the lifestyle shifts they brought with them. 

For example, humans have eaten foods like fruits, nuts, seeds, and lean meats for millions of years [8]. Refined sugars and starches, staples in food today, are recent additions to our diet. Similarly, our ancestors weren’t constantly plugged into social media. Humans roamed in groups of 50 to 150 individuals, but now, most people live alone or with a few family members. The list goes on. 

All of these changes are recent in evolutionary terms. It takes hundreds of generations for traits adapted to new conditions to evolve [7]. Social media or artificial sugar not only have negative impacts in themselves, but our physiologies have not yet adapted to them. These novelties trigger our stress response in a low-grade yet ongoing way [8].

Long-term health effects of nervous system dysregulation

Our bodies can't tell the difference between agitating, yet solvable problems and acute dangers [9]. As a result, we respond to harsh comments on social media or blaring horns in traffic as if they were life-threatening. Even minor stresses, when chronic, can significantly impact our quality of life.

With regular stress, our bodies direct attention away from anything irrelevant to escaping danger. Consequently, chronic stress can impair critical processes, such as immune regulation and digestion [10]. These disruptions can cause downstream negative health consequences, increasing our risks for conditions like chronic pain, insomnia, and other issues [11]. Chronic stress can also interfere with memory, learning, and cognition, making it harder to focus on our work or develop creative solutions to problems [12]. 

Stress can even change the way we register information in our surroundings. In neuroscientist Dr. Stephen  Porges’ terminology, this process happens through neuroception, an automatic risk evaluation system [13]. Unlike perception, which is a cognitive, conscious process, neuroception refers to implicit bodily feelings or sensations that deliver cues about potential risks in the environment. Neuroception produces what we might call gut feelings: that sense of being on-edge without knowing why. 

When we become accustomed to stress, our neurology can begin registering threats even in their absence. In some cases, this state of hypervigilance will interfere with our perception of the environment or social cues [13]. For instance, you could perceive criticism in neutral statements or read anger in calm facial expressions. Since these effects happen outside of conscious awareness, we need to reverse them by communicating directly with the nervous system.

Key principles for regulating your nervous system

In a survival-focused mode, we lack the resources to do creative or explorative activities, which are impossible without a foundational sense of safety. And emotional safety depends on the ability of the nervous system to turn off our defensive systems [13]. 

Fortunately, because of the connections between the neocortex and the ANS, we can influence the state of our nervous systems. But doing so requires more than thinking positively. To change our state, we need to send our nervous system what stress psychologists call “signals of safety," or ways of letting the ANS know we're not in danger. 

The principles below can help you train your body to rapidly bounce back from stress. Over time, you may also find yourself much less reactive to situations that once triggered high levels of tension. 

Improve your vagal tone

In our productivity-focused society, it's easy to lose a sense of grounding within your body. This is especially true if you do knowledge work. One way to ground yourself physically is to improve your vagal tone through a vagus nerve reset or other vagus nerve-focused exercises. 

The vagus nerve is the longest nerve in the ANS. It is also one of the most important (and complex) cranial nerves in the body. The vagus nerve forms a two-way line of communication between the brain and many major organs. It regulates involuntary processes: digestion, heart, blood pressure, respiratory rate, and other processes. [14]. 

The term vagus is Latin for “wandering.” Its name refers to its extension from the base of the brainstem throughout the body. As mammals evolved, the vagus nerve grew new branches, leading to our developing nuanced perceptual skills, like the ability to read layers of meaning in facial expressions or vocal intonations [14], among other things.

As a primary component of the parasympathetic branch, stimulating the vagus nerve can help you reset your nervous system, signaling to your body that it’s safe to initiate rest-and-digest functions. Here are a few ways to stimulate the vagus nerve:

• Take long, slow exhales. During slow exhales, we engage what’s known as the vagal brake, which affects the heart’s pacemaker, slowing down its electrical impulses [4]. This engages our parasympathetic response and results in a feeling of calm. Mind-body practices involving controlled breathing, such as pranayama yoga, can also increase vagal tone for the same reason.

• Sing. More than a form of self-expression, when we sing, our exhales become slower than our inhales. Like long, slow exhales, singing slows the heart rate. Also, since the vagus nerve connects to the muscles of the back of the throat, humming, playing wind instruments, gargling, and chanting can all stimulate the vagus nerve [4]. 

Raise your heart rate variability (HRV)

HRV measures the variation between heartbeats. It emerges from the heart’s responses to competing signals from the sympathetic and parasympathetic systems. 

A high HRV indicates the body is responding equally to parasympathetic and sympathetic signaling, meaning it can respond robustly to changing demands [3]. A consistently high HRV promotes mental clarity, focus, stamina, and more.

Some ways to improve your HRV include:

• Optimizing your sleep. Our level of stress resilience depends on the quality of our sleep. Getting about 20 minutes of sunlight after waking can improve the quality and consistency of your sleep. Morning sunlight helps align internal rhythms with the time of day, promoting wakefulness during the day and sleepiness when it gets dark [15].

• Eating a balanced diet. Research in Behavioral Pharmacology measured relationships between nutrition and HRV. They found that foods high in omega-3 fatty acids, such as eggs, walnuts, and cold-water fatty fish, along with B vitamins and probiotic sources, had long-term benefits for HRV [16].

• Using stress wearables like Apollo. The Apollo sends soothing frequencies that help balance the nervous system through the body’s response to touch. With consistent use, the Apollo trains your nervous system to bounce back faster from stress via its effects on HRV.

Honor your connections

Humans are social creatures. As described in the journal Infant and Child Development, social isolation disrupts our ability to regulate our physiological state [17]. In this sense, our alienation from those around us represents another novelty of the modern world. For most of human history, we lived among large groups. 

It’s not surprising, then, that many studies report that social isolation and loneliness pose a similar level of risk to health as smoking or high blood pressure [18]. 

One important way relationships balance our nervous system is through touch. Touch stimulates receptors that communicate with the vagus nerve. This interaction evokes a parasympathetic response, slowing the heart rate and decreasing blood pressure [19]. 

As a result, touch powerfully influences our emotional state. In 2017, Scientific Reports published research suggesting that slow, gentle touch (as opposed to a fast, “neutral” touch) lessened feelings of social exclusion [20]. The authors didn’t change any other variable except the nature of the touch, suggesting that a unique type of embodied, touch-based interaction can stimulate social bonds. 

These findings account for why hugging and other forms of physical contact can transform your mood after a difficult day. 

Too long; didn’t read

Although circumstances can certainly cause stress, it’s often a response to processes happening well beneath the surface of our conscious minds. Since we’re all subject to a novel, rapidly changing modern environment, stress relief techniques that promote direct communication with the ANS have never been more valuable. 

By shifting the way you breathe, optimizing your HRV, and honoring your connections, you can regulate, rather than manage or suppress, your emotions. This can not only help you recover from stress faster but promote trust in your body’s natural ability to regain balance during challenging times.

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