The term ‘fight or flight’ is widely recognised as the body’s stress response, signaling a state of alertness and readiness to either flee or confront a perceived threat. But how deeply do we understand the mechanics of this ‘fight or flight’ reaction, and the effects it has on our bodies and minds?
This stress response, ‘fight or flight’, is an evolutionary mechanism that enabled our ancestors to survive threats like predators in the challenging environments they inhabited.
In contemporary times, though, our stressors differ significantly. They usually don’t pose a direct threat to life but can profoundly affect our wellbeing. Unlike the clear and present danger of a sabertoothed tiger, today’s stressors are more persistent, confronting us on a daily or hourly basis without the same tangible resolution.
Here’s a list contrasting modern-day stressors with those of our hunter-gatherer ancestors:
Workplace Pressure vs. Predatory Threats:
- Modern: Stress from deadlines, performance reviews, job insecurity.
- Ancestral: Immediate threats from predators or rival tribes.
Social Media and Information Overload vs. Survival Information:
- Modern: The constant influx of news, social comparisons, and digital communication.
- Ancestral: Necessary information for survival like tracking prey or finding water sources.
Financial Worries vs. Resource Scarcity:
- Modern: Concerns about bills, debt, and economic stability.
- Ancestral: Finding enough food, shelter, and basic resources for survival.
Traffic and Urban Crowding vs. Open Natural Spaces:
- Modern: Stress from commuting, traffic jams, and living in densely populated areas.
- Ancestral: Navigating and living in wide, open natural environments.
Chronic Health Concerns vs. Acute Health Threats:
- Modern: Anxiety over long-term health issues like obesity, heart disease, diabetes.
- Ancestral: Immediate health threats from injuries or acute illnesses.
Environmental Pollution vs. Natural Environment:
- Modern: Concerns about air and water pollution, climate change.
- Ancestral: Living in a more pristine natural environment with fewer pollutants.
Relationship Dynamics vs. Small Community Living:
- Modern: Complex social relationships, online dating, and divorce.
- Ancestral: Tight-knit small community relationships with defined roles.
Educational and Career Competition vs. Skill Mastery for Survival:
- Modern: Pressure of academic achievement, career advancement, and job competition.
- Ancestral: Learning and mastering skills necessary for daily survival.
Sedentary Lifestyle vs. Physically Active Lifestyle:
- Modern: Stress related to a lack of physical activity, obesity, and health issues.
- Ancestral: Active lifestyle involving hunting, gathering, and moving regularly.
Sleep Deprivation vs. Natural Sleep Patterns:
- Modern: Stress caused by insufficient sleep due to artificial lighting, screens, and work schedules.
- Ancestral: Sleeping according to natural light cycles and physical exhaustion.
So, what is happening under the hood?
Here’s a simplified process of the body’s ‘fight or flight’ stress response:
Perception of Threat:
- When the brain perceives a threat or stressor, it sends signals to the adrenal glands, which are located on top of each kidney.
Activation of the Sympathetic Nervous System:
- The brain activates the sympathetic nervous system, triggering the release of a neurotransmitter called norepinephrine. This prepares the body for immediate action in response to the perceived threat.
Adrenaline Release:
- The sympathetic nervous system stimulates the adrenal glands to release adrenaline (epinephrine) into the bloodstream.
Effects of Adrenaline:
- Adrenaline prepares the body for quick, intense physical activity. It has various effects, including:
- Increased heart rate: Enhances blood flow to deliver oxygen and nutrients to muscles.
- Dilation of airways: Improves oxygen intake.
- Increased blood flow to muscles: Prepares muscles for physical exertion.
- Dilated pupils: Improves vision for heightened awareness.
Activation of the HPA Axis:
- Simultaneously, the brain activates the Hypothalamus-Pituitary-Adrenal (HPA) axis in response to the stressor.
Release of Cortisol:
- The hypothalamus releases corticotropin-releasing hormone (CRH), which signals the pituitary gland to release adrenocorticotropic hormone (ACTH).
- ACTH then stimulates the adrenal cortex (outer part of the adrenal glands) to release cortisol into the bloodstream.
Effects of Cortisol:
- Cortisol has longer-term effects compared to adrenaline and is involved in regulating the body’s metabolism. Its effects include:
- Mobilisation of energy stores: Cortisol increases the availability of glucose in the bloodstream for energy.
- Suppression of non-essential functions: Cortisol temporarily suppresses functions like digestion and the immune system to prioritise resources for immediate needs.
Return to Baseline:
- Once the threat has passed, the body’s parasympathetic nervous system helps restore balance by promoting relaxation and recovery.
This complex interplay between the sympathetic nervous system, adrenaline, cortisol, and the HPA axis is crucial for the body’s adaptive response to stressors.
Understanding the mechanisms of the body’s stress response is crucial for several reasons.
Our biological responses to perceived threats were originally designed for a very different environmental context compared to today’s world. If we revisit the list of modern-day stressors, it’s evident that our bodies now frequently encounter stressors which our ancestors never faced. The aspect of our ancient stress response that allowed us to ‘return to baseline’ occurs less often in our current lives. Many of us are living in a ‘fight or flight’ state for extended periods – hours, days, weeks, months, or even years. When we exist in this state for too long, our bodies continuously trigger neurochemicals and stress hormones. This process suppresses essential functions that are vital for maintaining good health and overly activates other bodily functions, leading to chronic health conditions.
While the immediate effects of adrenaline, such as increased heart rate, dilation of airways, and increased blood flow to muscles, are beneficial in short-term, fight-or-flight situations, their long-term activation can lead to various health issues:
Increased Heart Rate:
- Short-term: Prepares the body for rapid action.
- Long-term Effects: Can lead to chronic heart conditions like hypertension (high blood pressure), increased risk of heart attack and stroke, and overall strain on the cardiovascular system.
Dilation of Airways:
- Short-term: Allows more oxygen into the lungs to enhance physical performance.
- Long-term Effects: Chronic stress may exacerbate respiratory problems such as asthma. In some individuals, prolonged stress can also lead to hyperventilation and panic attacks.
Increased Blood Flow to Muscles:
- Short-term: Readies muscles for immediate physical exertion.
- Long-term Effects: Can cause muscle tension and pain, leading to chronic conditions like tension headaches, migraines, and musculoskeletal disorders.
And while cortisol plays a crucial role in managing stress by increasing the availability of glucose in the bloodstream for energy and temporarily suppressing non-essential functions like digestion and the immune system, its long-term presence can lead to several health issues:
Increased Glucose in the Bloodstream:
- Short-term: Provides immediate energy to cope with stress.
- Long-term Effects: Can contribute to conditions like hyperglycemia (high blood sugar levels) and increase the risk of developing type 2 diabetes. It also leads to increased appetite and weight gain, particularly around the abdomen, which is linked to a higher risk of heart disease and stroke.
Suppression of Digestive System:
- Short-term: Redirects energy away from digestion to deal with the stressor.
- Long-term Effects: Can lead to digestive problems such as gastritis, acid reflux, and irritable bowel syndrome. Prolonged stress can also negatively impact gut health, leading to an imbalance in gut flora and exacerbating digestive conditions.
Suppression of the Immune System:
- Short-term: Helps conserve energy to handle immediate stress.
- Long-term Effects: Weakens immune responses, making the body more susceptible to infections and illnesses. It can also slow down the healing process and may exacerbate autoimmune conditions.
The importance of understanding how today’s world continuously triggers our body’s ancient stress response, and the impact of this prolonged stress on our bodies and minds, cannot be overstated. By becoming more aware of these triggers and our biological responses to them, we can recognise the critical need to find practices that effectively manage and mitigate stress.