Life is full of stressors, but we are usually resilient enough to handle stress and the ups and downs of it. It goes a bit like this: emergency, recovery, emergency, recovery. The stress response is adaptive and designed to help you survive in times of life-threatening danger, and then recover from stress to help you return to normal and thrive. The problem nowadays is that recovering can be really challenging since there are so much stressors. In many people the alarm bells never go off and they get stuck in a perpetual state of unrelenting stress and high cortisol. But how does the stress response actually work and what is the role of the nervous system?

The nervous system

The autonomic nervous system (ANS) is a branch of the nervous system that is governed by your subconscious. You can’t get there and instruct it. It regulates processes like heart rate, blood pressure, and hair growth. The ANS is divided into three branches, the sympathetic nervous system (SNS), the parasympathetic nervous system (PNS), and the enteric nervous system (ENS). Let’s dive deeper into the first two.

Fight-or-flight mode

Stressors such as illness, injury or a stressful life event like a divorce or even a positive event like having a baby, trigger the sympathetic nervous system (SNS), also known as the ”fight-or-flight” mode. This stress response is adaptive, and it’s literally designed to keep you alive. Every time the body experiences a stress, big or small, the adrenal glands pump out stress hormones to help the body deal with what it perceives to be a life-threatening event. Whether you’re being chased by a lion, you’re going through that divorce, or you’re just stuck in traffic, your adrenals are producing the same response. You’re officially in fight-or-flight mode. This disrupts your circadian rhythm and restorative sleep to keep you ever so slightly awake, increases inflammation to protect you from germs and also resists insulin so more glucose goes to your brain. The functions in your body that are secondary to immediate survival like growth and tissue repair, but also digestion and fertility are shut down. The body assumes that you’re fighting for your life so you’re not going to be eating meals, let alone reproduce.

Rest-and-digest mode

The parasympathetic nervous system (PNS), also known as the ”rest-and-digest” mode, is activated when we feel safe and are surrounded by people we trust and love. It’s also being activated by diaphragmatic breathing (breathing deep into the belly). The longer the exhalation, the better the parasympathetic nervous system engages. When we breathe diaphragmatically it communicates to every cell in our body via our nervous system that we are safe. Being in parasympathetic state helps us recover from stress and allows for secondary functions like growth, tissue repair, digestion and fertility to come back online.

Types of stress

There are different types of stress: physical, physiological, and perceived stress.

Physical stressors:
• Poor nutrition and nutrient deficiencies
• Illness
• Excessive training
• Injury
• Exposure to toxins
• Poor sleep
• Underlying gut issues

Emotional stressors:
• Stress about work, health, relationships, finances, etc.
• Being overloaded with information
• Lack of control
• Losing a loved one
• Trauma
• Emotional stressors like anger, frustration, shame, worrying

Perceived stress
The extent to which people feel that the demands placed on them are beyond their capabilities. It’s the perception of pressure that is the main culprit.

All of these types of stress can send us into chronic sympathetic activation and a fight-or-flight state, contributing to health issues. These stressors are difficult to recover from and changing them often requires time and effort

The stress response

The sympathetic nervous system is designed to protect us and give our bodies and brains the tools they need to escape danger and stay alive. When we experience a stressor, our body launches into sympathetic activation. In an instant, the amygdala (a small part of the brain that regulates emotions) sends a sort of SOS signal to the hypothalamus, which is kind of like a central command center for the fight-or-flight response. Through a complex web of communications, called the hypothalamic-pituitary-axis (HPA axis), this signal makes its way to the adrenal glands, which start producing adrenaline, leading to instant physiological changes and feelings that we all recognize. For example, your heart rate increases, your muscles tense, your breathing becomes shallower, glucose is released into our bloodstream, and our digestion slows down so we can direct blood and energy to other areas of the body. Your lungs even expand their capacity so you can get the most oxygen in the fewest possible breaths. All of this happens in an instant. You have that surge of adrenaline and are ready to fight or flight. If the threat doesn’t immediately pass, the HPA axis activates another series of communications to keep the sympathetic nervous system activated for more than just a few seconds. This leads to the release of cortisol. Cortisol has beneficial short-term effects, but chronically elevated cortisol levels can have harmful long-term effects. It is therefore extremely important to prevent long-term cortisol levels.

What are you noticing?

• Weight gain/trouble losing weight – your body is saving reserves because it is unsure when there’s going to come in more food, and it needs all the fuel it can get to fight or flight.
• Sugar cravings – glucose from sugar is the best fast-burning fuel for the body so the body wants more of it, so your muscles have enough fuel to run and the brain has enough fuel to think.
• Bloating & constipation – digesting your foods properly isn’t a priority during stressful times and digestion get shuts down.
• Irregular or missing periods – more on that in The Impact of Stress on Menstrual Symptoms.
• Acne/breakouts – all the blood supply is diverted into saving your life and so is the oxygen distribution and the distribution of nutrients. Having a clear skin is not a priority for your body.
• Difficulty falling or staying asleep – if you would be in real danger and something would come out of the jungle and threaten your life, you wouldn’t wake up in time to save your own life. This makes restorative sleep not a priority and high stress hormones will keep you ever so slightly awake.

When we suffer from chronic stress, our sympathetic nervous system is constantly activated, our adrenal glands are constantly pumping out stress hormones, and our parasympathetic nervous system rarely has a chance to kick in and help us wind down. In the end it comes down to a simple thing: Stress is stress. Whether that is stress from lifestyle or from exercise. The more stress you’re putting on yourself from lifestyle, the less stress you’ll be able to put on yourself from exercise, and vice versa.