anxiety symptoms and causes

The Science of Anxiety

The human brain is a complex and fascinating organ that serves as the body’s command center and allows us to process information and formulate thoughts and feelings. We are constantly processing and adapting to our environment, which changes our thoughts, feelings, and behaviors. It is important to understand that anxiety is actually a natural emotional response to our environment when we feel we are under threat. In this way, anxiety can be protective and help us to understand and adapt to the world around us.

Understanding what causes anxiety

Understanding what causes anxiety

Before we get started, here are the main takeaways:

  1. Anxiety is a natural human response - all humans have it. When you experience persistent anxiety that interferes with your ability to cope, it simply means your body is working overtime - and the good news is that this can be reset.
  2. Anxiety is not just in your head. It is a physiological response (or normal bodily response), and we must shift away from the perspective that we can entirely control anxiety through our thoughts.
  3. The notion that anxiety is consciously controlled and that we can change how we think is inaccurate and detrimental to our well-being. 

Anxiety as a natural response

We often take an unrealistic amount of personal responsibility, ultimately feeling defeated when we cannot seem to get things under control. The truth is that much of our functioning is outside of our conscious control. Here’s a fascinating fact:

“The human brain can process 11 million bits of information every second. But our conscious minds can handle only 40 to 50 bits of information a second (NPR, 2020).” 

Can you imagine being aware of up to 11 million things per second? I am not sure about you, but this seems overwhelming and would probably leave us lost in our thoughts. Thankfully our body has automatic systems to help us function. Anxiety is one of the ways that our body automatically responds to the information being processed, particularly when our brain senses danger. 

Since anxiety is a natural, instinctual, and automatic response, it is worth understanding the science. So let’s look at the foundation of how our mind, body, and emotions work together.

The gut-brain connection

Our brain not only processes information but makes split-second decisions on how to respond, but it does not do this alone. Our brain works closely with our gut, called our second brain. The brain and our gut constantly send information to each other since they are both processing centers. 

Think about it: when you feel something, react to a situation, where do you feel it? Often time in our stomach. So understanding the gut-brain connection is key to understanding anxiety. To best understand this, let’s use an analogy: the highway.

Let’s imagine that there is a highway that starts at the brain and ends at our gut. Information travels back and forth, but instead of having cars traveling on a highway, we have neurons, and rather than concrete, we have nerves. 

To recap: neurons transmit signals between our main processing centers through our nervous system. The nervous system has two main components: the central nervous system and the peripheral nervous system. 

The brain and spinal cord, and central nervous system (CNS)

The gut-brain highway is located in our spine. Our brain sends and receives messages by transmitting signals that travel up and down our spine to the rest of our body. The purpose and function of this highway are a simplified explanation of our central nervous system. 

The peripheral nervous system (PNS)

Back to the highway analogy: a highway is somewhat of a shortcut that allows us to travel quicker. Each exit is connected to a bunch of other streets that let us get to exactly where we want to go. The human body is similar; our central processing system, the CNS, is connected to another system: the peripheral nervous system.

In other terms, our PNS consists of nerves that branch off our spinal cord to the rest of the body (for example, the nerves that give your fingers sensations.) This system branches off into two:

  • The autonomic nervous system
  • The somatic nervous system 

The Autonomic Nervous System (ANS)

Information travels through these systems to different parts of the body for several various reasons. Sometimes we travel down a highway to get home; we get off the exit and travel down familiar roads. Other times, we are exploring or maybe even lost, which is a very different experience. Sometimes we are on autopilot, and other times, we are alert. Our body has an autopilot system, the Autonomic Nervous System. 

This system is in charge of all of the necessary functions that we do not have to consciously think about, including regulating our:

  • heart rate
  • blood pressure
  • respiration
  • digestion
  • sexual arousal

Being on autopilot does not mean we don’t have to be aware of our surroundings. On the contrary, even on autopilot, we have to adjust or run serious risks. Sometimes we may have to speed up, slow down, or come to a complete stop. And yet again, the human body has a remarkable capacity to adapt and has a system for this too! 

The ANS system branches off into three:

  1. Sympathetic nervous system
  2. Parasympathetic nervous system
  3. Enteric nervous system

And this is where it gets juicy because all these systems control anxiety! 

Let’s take a moment of appreciation for the human body. Through these interconnected complex systems, we can feel and experience the world around us. So while anxiety is undoubtedly difficult, it is simultaneously an incredible adaptive system we can learn to understand and manage. 

Wondering how to manage and control your anxiety naturally? 

Stay tuned for upcoming blog posts on the sympathetic, parasympathetic, and enteric nervous systems and tips to regulate your body naturally.


  • Waxenbaum JA, Reddy V, Varacallo M. Anatomy, Autonomic Nervous System. [Updated 2021 Jul 29]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from:
  • NPR. (2020, July 15). Understanding unconscious bias. NPR. Retrieved October 3, 2022, from,The%20human%20brain%20can%20process%2011%20million%20bits%20of%20information,bits%20of%20information%20a%20second


Written by Camila Smith, LCSW