Your Brain Under Stress

Let’s take a look at the neurobiology of stress. What happens to your brain under stress?

By Momentous Institute | Jan 20, 2021
Your Brain Under Stress 01

There’s no shortage of stressors in the world recently, so there’s a pretty good chance you’ve been feeling some stress. We all know what our bodies and minds feel like when we’re experiencing stress, but let’s take a look at the neurobiology of stress. What happens to your brain under stress?

Of course, the brain is the most complex organ in the human body and there’s no way we’d be able to fully explain every part of it. So what we’re diving into here is a simple version. That said, let’s talk about some basic parts of the brain and how the brain functions.

The brainstem is the lowest part of your brain that controls basic life functions like breathing, blood pressure, heart rate and body temperature. The brainstem is developed by birth, as it controls our life-sustaining functions.

The mid-section of the brain is known as the limbic system, often referred to as the emotional control of the brain. It does not apply any logic and does not have any real concept of time. Past, present and future are all the same to the limbic system.

The highest region of the brain is the prefrontal cortex, which controls logic and rational thought – it’s the part of the brain that allows decision making and complex thinking. This is the last part of the brain to develop; this region of the brain is fully developed by around the mid-20s.



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An important region to focus on when talking about stress is that middle region, the limbic system. Deep inside the brain is a small almond-shaped structure called the amygdala. The amygdala is the part of the brain in charge of the fight, flight or freeze reflex. One of its primary functions is to scan the environment and determine whether a certain stimulus is threatening or not, and respond accordingly.

In other words, the amygdala is constantly scanning the environment to protect you. It determines if sounds, movements, or environments are threatening. If you’re standing on a busy street corner, the amygdala is hard at work, protecting you from walking into the street until the cars have all passed. If you’re sitting at home in your living room, the amygdala may jump into action only at the sound of a loud noise.

The amygdala is designed to serve as an alarm clock – warning you that there’s danger, and then responding to the threat immediately by choosing to fight, flight or freeze (in other words, respond to the threat, leave the dangerous environment, or pause until the threat has passed). Then once the threat is gone, the amygdala can return to calm and the higher levels of the brain can resume their job of being in charge.

However, when you are experiencing a lot of stress, that amygdala stops functioning as an alarm, and functions more like a persistent alarm clock on snooze. It pipes up at a potential threat, and you may be able to calm it down, but a minute later, it pipes back up again about something else. It’s like constantly hitting snooze over and over all day long, rather than shutting the alarm off. The amygdala scans the environment and determines that everything is a threat. What was that sound? Why did that person look at me like that? Why does something feel off in this room? Things that normally the brain may miss entirely, the brain under stress notices and assigns as a threat.

Here’s the thing: the logical part of the brain is not in charge when we feel threatened. In fact, these upper regions of the brain (remember, the ones in charge of reasoning and complex thinking) essentially go offline. That means that when that alarm clock is ringing every few minutes, it interrupts our ability to think clearly. Our logical brain may know that a person’s body language is not threatening; the stressed brain may not.

So that was the neurobiological explanation for the brain under stress. Let’s talk about it in even simpler terms. How does the brain actually respond during a period of prolonged stress? You may recognize some of these symptoms in yourself or your loved ones.

  • -Easily agitated
  • -Numb or detached
  • -Tired, lethargic
  • -Reactive or aggressive
  • -Isolated or withdrawn

All of these responses fit within the fight, flight or freeze response. The brain responds to a threat and responds accordingly to protect you. Your brain may determine that shutting down and isolating is the most protective response, or may determine that aggression will help you. Since the limbic system is calling the shots, this is not a decision you are making using rational thinking and weighing of pros and cons. This is your brain’s automatic response to stress.



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So what can we do when we identify that our brain is experiencing stress? Some of the coping strategies to stress are those you’ve likely heard hundreds of times. That’s because they work.

Breathing is one of the easiest and most effective self-care strategies. This is not just something that sounds good, it’s linked to neurobiology. You can learn more about the science of breathing in this short video. Try this: take a long, slow breath in through your nose, filling up your lungs. (Try it!) Hold the breath for three seconds. Exhale slowly until all the air leaves your lungs. As you exhale, notice any areas in your body that feel tense – your jaw, fists, shoulders. Repeat this throughout the day, paying special attention to the tension in your body.

Another great tool for managing stress is to develop a plan. We’re much more likely to be able to take care of ourselves if we’re not responding new to each incident every time. Each week, or each morning, make a list of the stressful experiences that may be coming up throughout the day. If you know that a certain time of day is always stressful, or you have an important meeting or event that you expect will cause stress, jot it down. Then jot down how you will take care of yourself immediately before, during and after the experience.

Lastly, develop a support system. We are social creatures and our brains are actually designed to be social. One of the best tools we have for managing stress is to reach out to others. If you can’t be in person with loved ones, you can still gain the benefits of connection through regularly scheduled video calls or even a regular group text. You don’t have to talk about your struggles – though you certainly can – just communicating with others is a great way to alleviate the stress of life.

Additionally, don’t be afraid to ask for support when you need it. A trusted friend or colleague, your partner or a professional can help you process through stress and help get your brain back to a more regulated state.

While we can’t eliminate all of the stressors of the world, we can understand how our brain responds to protect us, and we can learn to manage our responses and live full, healthy lives even in the midst of stress. 



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