What is Stress and does it really matter?

“The greatest weapon against stress is our ability to choose one thought
over another.”

~ William James

Our body’s stress response is an adaptation for survival that has been developed over several million years to protect us. Back in our evolutionary past it was essential to help us deal with highly dangerous situations, such as being chased by a predator. Under times of stress, our body responds by activating our sympathetic nervous system, (our ‘fight or flight’ state) increasing mental acuity, sharpening all our senses, and increasing our stamina and strength. 

However, these physiological changes weren’t supposed to last long.  We have evolved to live most of the time in a relaxed state, punctuated by brief moments of stress.  The problem today is that, although we are not fighting off neighbouring tribes or being chased by a tiger, we experience perceived danger, fear or pressure in many everyday situations that are created by our modern lifestyle – pressure at work or school, financial worries, family or relationship problems, losing a job, etc etc. These continually trigger the stress state and this can have serious consequences for our health.

Many people don’t realise that it isn’t just emotional pressure that activates stress.  Just as relevant are the food choices we make.  Your gut bugs, your immune system and your brain are in constant dialogue whenever you eat anything.  It’s information, telling the brain whether or not the body is under attack from food that is potentially harmful. If we eat bad food, it responds by triggering inflammation.  This is one of our basic and ancient responses to stress. 

Environmental toxins, smoking, too much alcohol, overuse of antibiotics or other medications, lack of sleep and overtraining are other causes of the body becoming chronically stressed.  The body doesn’t discriminate between psychological and physiological stress - all these conditions cause the adrenal glands to pump out stress hormones. 

As a result, we are constantly triggering our ‘fight-or-flight’ mode (our sympathetic nervous system), and in so doing we are turning off our ‘rest-and-digest’ mode (the parasympathetic nervous system).  This latter is the state we are meant to be in most of the time, and it’s during this stage that we can digest properly, procreate, maintain mental and emotional clarity and repair the damage caused by the sympathetic overdrive.  

Our ancestor’s lifestyles achieved a natural balance between the parasympathetic and the sympathetic nervous systems.  Brief moments of stress from a hunt or attack from a predator were followed by plenty of time to relax and connect with peers, as most of them lived in extended-family groups. They would socialise while gathering food, cooking, and building shelter. Although their lives weren’t stress-free by any means, our ancestors knew how to rest and recharge. 

In contrast, we, with our super busy lives, do not prioritise relaxation.  Failing to shut off the sympathetic response is like burning out a motor.  Eventually the wear-and-tear causes the system to overload, resulting in damage that manifests as chronic disease.  

What happens physiologically in each mode?

The sympathetic nervous system (SNS) prepares your body to either run from danger or fight back.  It is activated in response to mental or physical stress.  It is first detected by a part of the brain called the hypothalamus.  When it detects stress the hypothalamus releases a hormone that sends a stress signal to another part of the brain, the pituitary gland, which in turn sends a signal to the adrenal glands, which sit on top of your kidneys.  The adrenal glands then release stress hormones cortisol and adrenaline.  These put you into the ‘fight or flight’ state so that you are primed to deal with danger.  This line of signalling is commonly known as the HPA (hypothalamus-pituitary-adrenal) axis.

• Blood pressure, heart rate and blood flow increases to help transport blood and oxygen to the brain, lungs, heart and muscles, making us stronger, faster and able to move away from perceived danger

• Brain moves to high-alert status, its function improved by a combo of additional blood flow and cortisol

• Blood flow decreases to the digestive and reproductive systems as these are non-essential functions for survival

• Glucose is rapidly released from the liver to be burned for quick energy in the muscles and the brain (to escape from the tiger)

• Insulin resistance is increased in the short term to prevent your body storing glucose, thus keeping it in the blood stream and therefore more readily available

• Inflammation (short term) as your immune system fires up to help you deal with an imminent threat and the possibility of injury and infection

The parasympathetic nervous system (PNS) is (or should be) our default mode, activated after a meal or in response to pleasure, and only when the effects of SNS go into retreat.  Its physical effects are generally opposite to those of the SNS reaction:

• Heart rate and respiration slow

• Blood pressure drops

• Intestinal activity increases

• Blood flow increases to the digestive tract

• Neurotransmitters like acetylcholine, which regulates muscle contractions, including cardiac muscle, are released

• Stress hormones decrease

• Sex hormones (libido) return to normal

These two systems are key parts of the Autonomic Nervous System that controls all our unconscious bodily functions as well as every organ in our body. To say that SNS and PNS are antagonistic is an oversimplification; the two systems can work with each other, against each other, or even independently of one another in order to maintain homeostasis (equilibrium) throughout the body.  It’s all about balance.  (1)  

What does Chronic Stress cause?

When we talk about stress, we think it is ‘all in our head’, but stress has specific and measurable biological impacts on the body. What does it cause? The short answer is “just about everything”.  It would take volumes to explain the full effects of stress.  (One of the best books on the subject is When the Body Says No: Exploring the Stress-Disease Connection by Gabor Mate).  

Here are some of the more common symptoms: tiredness, headaches, muscle tension, insomnia, mood swings and irritability, irrational fears and anxiety, hunger and sugar cravings, caffeine cravings, short term memory problems and digestive issues (constipation, diarrhoea etc).  But these are just symptoms; what stress actually causes is rather more alarming:

• Weakened immune response – the autonomic nervous system regulates the immune system in various ways.  High cortisol from continuous SNS stimulation suppresses immune function and can make the body susceptible to autoimmune conditions such as rheumatoid arthritis.

• Insulin Resistance, caused by chronically elevated glucose levels and the body’s reluctance to store glucose away

• Depression, anxiety and mood imbalances, caused by the brain being on long term high alert.  You start to worry about everything and see danger when no danger is present 

• Chronic high blood pressure, which changes the shape and size of blood vessels.  Increases the risk of many diseases but particularly heart disease and stroke

• Hormone imbalances due to long term diversion of resources.  This will contribute to a wide range of hormonal issues such as lack of libido and menopausal symptoms

• Digestive problems due to attention being diverted from digestion for too long (constipation, diarrhoea, indigestion and IBS)

• Memory loss – prolonged release of cortisol starts to kill neurons in the hippocampus, the brain’s memory centre, causing it to shrink. (Good news – it can grow back if you lower your cortisol levels). It also impacts the functioning of the pre-frontal cortex, which controls critical thinking and executive function

• Chronic Inflammation.  This condition is at the heart of many serious complaints, whether it be insulin resistance, obesity, type 2 diabetes, high blood pressure, and depression

• Thyroid problems. Elevated cortisol inhibits ability to convert thyroid (T4) into the active form (T3), slowing down metabolism and increasing weight gain. (When women have tried literally everything to lose weight but can’t, stress is often the culprit. It is metabolically impossible to lose weight when cortisol is high)

• Cancer. Stress causes cancer to proliferate because it feeds inflammation, tumour growth and metastases. Women with advanced breast cancer who have abnormal levels of cortisol are significantly more likely to die sooner than patients with normal cortisol, Stanford Uni researchers reported in 2000.

How can we objectively measure our stress levels?

Measuring cortisol is a good place to start.  It reacts quickly to stress and is a reliable indicator.  It can be measured in the blood, urine and saliva; the saliva test, while being non-invasive, is actually reliable.

The other test that has proven to be a good measurement of overall stress is Heart Rate Variability (HRV).  Unlike heart rate, which reports the average number of beats per minute, HRV measures the subtle variations in the time interval between individual beats.  It is measured with a heart rate monitor and can calculate small fluctuations in stress on a daily basis.  Not all wearable health trackers measure HRV, but more sophisticated ones such as the Oura ring can.

People often think that our heart should beat like a metronome, following a strict rhythm.  This isn’t so.  The strength of each beat and amount of time between beats should vary.  In general, higher HRV indicates better health and better autonomic balance.  Low levels of variability means our body is in a stressed state, and has been linked to multiple poor health outcomes.  Many things can lower HRV such as infections and inflammation as well as trauma, but for the vast majority of us, what affects our HRV the most is the relentless daily bombardment of small doses of stress that leave us feeling drained. 

Heart rate variability is often referred to as ‘vagal tone’, named after the vagal nerve – the longest nerve in the body, which comprises 75% of the entire parasympathetic nervous system. 

So, does Stress really matter?

I hope I have persuaded you that it does. 

Dysregulated cortisol affects your mood, your focus, your sleep, your fertility, your metabolism, your weight, your toxicity, and your immunity.  Long term, the consequences of stress can be devastating for your health, playing a significant role in the development of obesity, type 2 diabetes, high blood pressure, heart disease, strokes, cancer and Alzheimer’s.  It is also a key player auto-immune disease as well as many mental health disorders such as burn-out, anxiety and depression.   The WHO calls stress ‘the health epidemic of the twenty-first century. 

Despite these risks, many of us are blasé about stress.  It has become the norm of modern day living.  We think we can get away with it.  The reality is very different. 

Managing down your stress is the MOST important step you could take to improve your health.   I hope I can help you to take that step.

---