Whether it’s a racing pulse, tense muscles, or trouble sleeping, stress impacts everyone differently. No matter how you experience stress, these symptoms and more are a result of your body’s stress response.
Fight or Flight
Being able to respond quickly to a threatening situation could be a matter of life and death, which is why the stress response has such a powerful effect on the body. Often referred to as the “fight or flight” response, a coordinated whole-body reaction is triggered when you perceive a threatening or challenging situation. This response primes the body to either fight off danger or out-run it.
Imagine crossing a street to find yourself suddenly facing oncoming traffic. Before you can say “Yikes!”, your heart starts pounding, your breathing quickens, and your muscles tense, allowing you to get to safety fast. Body systems that help you respond in an emergency, like your muscles, heart, and lungs, get extra energy and blood flow. Functions that are less important during a short-term emergency, like digestion and immune function, get dialed back to conserve energy (1).
Key Players in Your Body’s Response to Stress
The body’s response to stress begins in the brain and is communicated throughout the body by stress hormones.
Amygdala
The first part of your brain to perceive a threat is an almond-shaped structure called the amygdala. This structure receives information from your senses and can trigger an immediate response before you are consciously aware there’s something to be stressed about (2). You might be familiar with this effect if you’ve ever felt like you reacted to a dangerous situation on instinct before you knew exactly what was going on.
Hypothalamus
The amygdala has a direct line of communication with the hypothalamus, a major control center of the brain (3). Generally, the hypothalamus keeps the body in balance by monitoring essential functions like heart rate, blood pressure, and body temperature. It also signals the pituitary, often called the body’s master gland, to release hormones. When a stressful situation occurs, the amygdala sends an alarm signal to the hypothalamus. A few seconds later, the hypothalamic-pituitary-adrenal axis, or HPA axis, is activated to coordinate a stress response throughout the body (3).
HPA Axis
The HPA axis refers to the interaction of the hypothalamus and pituitary gland in the brain with the adrenal glands located on top of the kidneys. The HPA axis is responsible for taking a stressful situation recognized in your brain and adjusting systems throughout the body to help you respond. Once the HPA axis is activated, the adrenal glands produce the hormones adrenaline and cortisol, which are the main drivers of the body’s response to stresses that last more than a few moments (3).
Adrenaline and Cortisol
A rush of adrenaline primes your body for action by increasing your heart rate, elevating your blood pressure, and boosting your energy supply (4). In coordination with adrenaline, cortisol raises the amount of sugar in your blood to ensure there’s plenty of fuel available to help you meet whatever challenges are coming your way. Cortisol is also responsible for dialing back the body’s functions that aren’t essential in an emergency such as digestion and immune function (4).
Chronic Stress: When Modern Life Hijacks Your Stress Response
The stress response coordinates practically every system in the body to help you react in an emergency. Once the stressful situation is resolved, the body’s stress response shuts down, and your heart rate, blood pressure, hormones, and other systems quickly return to normal.
Our stress response is a big part of what makes us so good at handling big challenges and threatening situations. Still, as life becomes increasingly complex, many of the problems that can activate our stress response have no easy solutions. Outrunning a dangerous animal is not the same as dealing with long-term financial problems, for example.
For many of us, it can feel like our stress response never fully shuts down. Stress hormones like cortisol can remain elevated for people who are facing ongoing stress. The short-term adaptations that help the body in an emergency, like elevated blood pressure or blood sugar are not as helpful when they don’t return to normal levels. Chronic stress takes a toll on the body and has been linked to an increased risk for health problems (5).
Stress Less
The body’s stress response is there to help you when you need it most but can lead to problems if it’s activated all the time. Life’s challenges aren’t likely to go away, but you can protect your wellbeing by learning to manage stress. Taking time to relax, connect with friends and family, and invest in self-care can make all the difference. Research suggests that regular exercise, yoga, or simple approaches such as mindfulness can have a positive effect for managing stress in a healthy way (6).
There’s a lot going on in your body when you’re feeling stressed. While modern life sometimes leaves us feeling too much stress, our body’s ability to respond to a stressful situation is a good thing. Taking a little time to focus on self-care and relaxation might be all you need to bring yourself back in to balance.
References
- Yaribeygi H, Panahi Y, Sahraei H, Johnston TP, Sahebkar A. The impact of stress on body function: A review. EXCLI J. 2017;16:1057-1072.
- Ohman A, Carlsson K, Lundqvist D, Ingvar M. On the unconscious subcortical origin of human fear. Physiol Behav. 2007;92(1-2):180-185.
- Chrousos GP. Stress and disorders of the stress system. Nat Rev Endocrinol. 2009;5(7):374-381.
- Miller WL. The Hypothalamic-Pituitary-Adrenal Axis: A Brief History. Horm Res Paediatr. 2018;89(4):212-223.
- McEwen BS. Neurobiological and Systemic Effects of Chronic Stress. Chronic Stress (Thousand Oaks). 2017;1:2470547017692328.
- Carlson LE, Toivonen K, Subnis U. Integrative Approaches to Stress Management. Cancer J. 2019;25(5):329-336.
