What Causes Stress?

Stress can be felt through a range of physical and mental symptoms; a pounding heart, sweaty palms, butterflies in your stomach, inability to think straight, or feeling panicked are some examples of symptoms of stress. There is no doubt that stress is an unpleasant feeling that most people would rather avoid!

In this blog, we'll look at why stress is more than just an unpleasant feeling; why we experience stress in the first place, and what you can do about it.

The Biological Reason for Stress

While persistent stress is detrimental, short bursts of stress are actually part of being human! From an evolutionary perspective, the stress response is a survival mechanism that enabled our primitive ancestors to react quickly to life-threatening situations.

The body's response to a perceived threat triggers a near-instantaneous sequence of hormonal and physiological changes that help someone fight off the threat or escape to safety. The stress response is often referred to as "fight or flight".

Unfortunately, the body can also overreact to stressors that are not life-threatening, such as relationship problems, work pressure, or social isolation.

The Nervous System and Stress Hormones

The stress response begins in the brain. When someone confronts a real or perceived danger, the body sends information to the part of the brain called the amygdala, an area that contributes to emotional processing.

When the amygdala perceives danger, it instantly sends a distress signal to another area of the brain, called the hypothalamus. Once the hypothalamus receives a distress signal from the amygdala, it activates a part of the nervous system called the sympathetic nervous system.

One of the well-known effects of chronic stress is that it actually increases the size of the amygdala, making the brain more receptive to stress. This creates a feedback loop where chronic stress makes you more receptive to stress.

The sympathetic nervous system sends signals to the adrenal glands which immediately pump adrenaline into the bloodstream. As adrenaline circulates through the body, it creates rapid physiological changes including increased heart rate and blood pressure, faster breathing, and opening of small airways in the lungs. Blood flow is diverted to muscles, the heart and other vital organs. In short, adrenaline gets your body ready to fight or flee from real or perceived danger. It is the rapid release of adrenaline in stressful situations that allows people to do things like jump out of the way of an oncoming car without even thinking about it.

As the initial surge of adrenaline subsides, the hypothalamus activates a second part of the stress response system known at the HPA axis. The HPA axis consists of the hypothalamus, the pituitary glands, and the adrenal glands.

The HPA axis is responsible for keeping the sympathetic nervous system - the "fear or flight" response, switched on. It relies on a series of hormones to keep the accelerator down. The hypothalamus releases a hormone called CRH (corticotropin-releasing hormone), which travels to the pituitary gland, triggering the release of another hormone called ACTH (adrenocorticotropic hormone). This hormone travels to the adrenal glands, prompting them to release cortisol. Cortisol is the hormone that tells the body to stay revved up and on high alert beyond the initial adrenaline rush. Cortisol acts like a sustained-release tablet, in fact, it takes a full 26 hours for cortisol levels to return to baseline after a stressful event.

When the threat passes, cortisol levels slowly start to fall. At the same time, the parasympathetic nervous system - the "brake" - then dampens the stress response and our body eventually returns to a normal, alert but relaxed state.

As you can see from the diagram below, the sympathetic and parasympathetic nervous systems are responsible for opposite effects. The sympathetic nervous system is all about ramping up our "fight or flight" response, whereas the parasympathetic nervous system is all about creating a more relaxed state.

In a perfect world, these two systems would work together to balance each other out. The sympathetic nervous system allows us to rapidly respond to threats when needed, and the parasympathetic nervous system allows our body to relax in the absence of stressors.

Unfortunately, the fast pace of modern life and constant information overload from digital media means that many people don't have a chance to switch off their "fear or flight" response. If you suffer from stress, you're not alone! In fact, the number of people who suffer stress has increased markedly over the last year and a half as the impacts of the pandemic have been felt all over the globe.

Why is Stress a Problem?

Short bursts of stress can sometimes be beneficial - for example, the extra edge an athlete gets when competing against others. However chronic stress can make a person feel embattled, nervous, anxious or less capable of responding to life's demands.

Chronic stress can lead to both physical ailments and psychological changes such as the increased risk of heart disease, high blood pressure, diabetes, depression, or anxiety. If that wasn't bad enough, chronically elevated stress hormones make the body store more energy - to get the body ready for the next stressful event. The upshot is increased appetite, often referred to as comfort eating, and increased storage of fat, resulting in weight gain.

When someone is chronically stressed, cortisol can build up in the brain and cause detrimental effects. Chronic stress impairs the brain in multiple ways. It can disrupt the way brain cells communicate with each other, resulting in reduced sociability and avoidance of interactions with others. Chronic stress kills off brain cells, reduces the overall size of the brain and selectively shrinks an area of the brain called the prefrontal cortex. This area of the brain is responsible for focus, planning and managing emotional reactions.

Chronically elevated cortisol from ongoing stress creates a sort of domino effect that hard-wires the brain to become more predisposed to be in a constant state of stress. As increasing health, economic and social pressures have swept the globe over the last year and a half, it is very clear that there has been a huge increase in stress. People report feeling worried, overwhelmed and cut off from loved ones.

The good news is, there are some simple steps you can take to override your brain's evolutionary wiring towards the "fight or flight" response and instead, help steer your brain towards the activation of the parasympathetic, or relaxed state.

How to Override Your Brain

As we have seen in the last section, our brains are evolutionarily wired to respond to perceived stressors with the "fight or flight" response. In some ways, our bodies want to feel stress because of the primal need for survival.

Missing a work deadline, having a few terse words with your partner, being stuck in traffic. Yes, they are all stressful, but none are life-threatening. The secret to reducing your stress comes down to overriding your primal brain's "fight or flight" response and preventing the amygdala from sending a distress signal to the hippocampus. In doing so, you're telling your brain that you're safe, there is no need to stress.

There are many ways of managing stress and there is no one size fits all. It comes down to your lifestyle and preferences, however, there are a few common themes that are helpful in finding what works for you.

Effective techniques for stress relief include yoga, mindfulness or taking a walk. What do these stress-relieving activities all have in common? They are all about overriding your brain's "fight or flight" response. Whether you are time-poor or have oodles of time available, there is a stress-reducing technique for everyone!