What is stress?

This article helps you to understand what stress is

Learning Outcomes:

• Understand the science of stress
• Understand how stress impacts your feelings, thoughts and behaviour
• Understand the different internal and external stressors and how you can manage them

Defining stress

Dr. Justin M. Nash and colleagues consider that “stress results from any challenge or threat, either real or perceived, to normal functioning. The stress response is the body’s activation of physiological systems, namely the hypothalamic‐pituitary‐adrenal axis, to protect and restore functioning”.

You will learn more about the hypothalamic‐pituitary‐adrenal axis below.

Stress can be simplified as: a response to demands that call for activation and the use of resources.

Stress is an integral part of growth and development; it can be positive and not necessarily harmful. Stress can help protect you, and it helps you rise to face your challenges. Mild, short-term stress helps us to be more alert, our thinking rate increases, concentration improves and our motivation and performance benefit.

The problem occurs when we experience long-term stress with no intermittent recovery (rest). Unbroken high stress and the resulting high alertness breaks down our body and brain and can lead to disease and exhaustion.

Chronic stress increases your risk of heart attack and stroke by up to 50%. Levels of activation are governed by the autonomic nervous system (ANS) which regulates our body’s systems in order to manage the demands of everyday life.

Your Body’s Nervous System

The ANS is a part of the peripheral nervous system (PNS), which is one of two parts of our overall nervous system. The other is the central nervous system (CNS) which integrates information together with coordinating and influencing the activity of all parts of our body.

The PNS consists of all the nerves outside of the brain and spinal cord (which houses the CNS). The main role of the PNS is to connect the CNS to the rest of the body (e.g our muscles, organs and the rest of the body).

The PNS also consists of the somatic nervous system (SNS) which is under voluntary control. It enables us to control our movement via controlling our muscles and it receives information from our senses.

The other part of the PNS is the ANS which self-regulates and influences the functioning of our involuntary organs such as the heart, lungs and digestive system.

Autonomic Nervous System (ANS)

The two sections of the ANS are the sympathetic and parasympathetic sections.

• Sympathetic: Activates and prepares the body to meet challenges (fight, flight). Like the gas pedal in a car.
• Parasympathetic: Restores our body and maintains the body’s resting condition (rest-and-digest and tend-and-befriend). Like the brake pedal in a car.

The biology of stress

Neuroception is a neural process that enables us to distinguish safe from dangerous contexts without the need for conscious thought (perception). More specifically, input from our senses and internal organs is sent to a part of the brain called the thalamus (which is like a sensory traffic controller).

The thalamus then sends signals to the amygdala (brain’s threat detector) and the pre-frontal cortex (conscious and deliberate brain system), via the sensory cortex (which adds meaning to what has been sensed). The amygdala immediately checks with the hippocampus (important for memory) to see whether the stimuli it has been sent correlates with previous threats.

This pathway is much faster than the pathway linked to the pre-frontal cortex and therefore the amygdala reacts before any direction is received from the pre-frontal cortex. This is commonly known as the amygdala hijack.

If there is a correlation (detection of a possible threat), the amygdala launches the fight or flight response.

First of all, the amygdala sends an emergency signal to the hypothalamus. The hypothalamus acts as a command centre, communicating with the rest of the body via the autonomic nervous system.

Alert — Sympathetic Nervous System

In the fight or flight response, the hypothalamus activates the sympathetic nervous system (gas pedal) by sending signals through it to the adrenal glands. The adrenal glands respond by releasing adrenaline into the blood.

Adrenaline causes an increase in heart rate, blood pressure, breathing rate and a decrease in heart rate variability (HRV). This results in raised levels of oxygen reaching the brain, which increases alertness and enhances our senses (e.g. sight, hearing, smell).

At the same time, glucose and fat are released into the bloodstream, delivering more energy to the body (especially the muscles in our limbs and heart). Blood is drawn away from our digestive system and any other system that is not directly related to our ability to survive in the moment.

This happens so quickly that before we are even consciously aware of what is happening, our body is able to respond to the threat. E.g. we are able to jump out of the way of a speeding car before thinking about what we are doing.

As we start to become aware of what we are experiencing, our pre-frontal cortex helps us to rationalise whether there is a real threat or not. If there is no threat, the parasympathetic nervous system (the brake pedal — see below), helps us to relax again. Adrenaline levels also lower again.

If a real threat is detected, the hypothalamus triggers the second component of the stress response system — the HPA axis is used to keep our gas pedal pressed down.

HPA — Hypothalamic-Pituitary-Adrenal

The hypothalamus releases corticotropin-releasing factor (CRF).

This chemical then binds to CRF receptors on the pituitary gland, which then releases adrenocorticotropic hormone (ACTH).

ACTH then binds to receptors on the adrenal cortex which produce cortisol. As a result, our heart rate, blood pressure, breathing rate remain higher and our heart rate variability (HRV) continues to be low.

Relaxation Response — The Vagus nerves and PNS

The parasympathetic nervous system is like a decelerator or brake pedal that helps us to slow down and relax.

The parasympathetic nervous system uses neurotransmitters such as acetylcholine to decrease the heart rate, blood pressure and slow our breathing. This deceleration is controlled by the vagus nerves and termed “vagal brake“.

The wandering nerves (Vagus is Latin for wanderer) originate at the base of the brain and branches its way down through the body into the digestive system. In this article, we will focus on the Ventral Vagal Complex part of the Vagus nerve (VVC).

Functions of the Vagus nerves

It is considered that the Vagus nerves are a key activator of the parasympathetic nervous system. This system restores our body and maintains the body’s resting condition (rest-and-digest and tend-and-befriend).

More specifically the vagus nerve provides the following functions:

• Helps regulate our heart rate and breathing (slows them)
• Maintains the functioning of our digestion system, including the contraction of the stomach and intestine muscles
• Sends information from our intestines and other organs to our brain
• Prevents excess inflammation by regulating our immune system

Christopher Bergland, states:

“From a simplified evolutionary perspective, one could speculate that our ancestors relied on the sympathetic nervous system to kickstart neurobiological responses needed to hunt, gather, and ward off enemies. Conversely, the parasympathetic nervous system probably fortified our innate drive to nurture close-knit human bonds, procreate, and build survival-based cooperative and supportive communities.”

Allostasis

Our brain manages our resources and creates a balance between the sympathetic and parasympathetic nervous systems.

The sympathetic nervous system is constantly on the ready to activate us, although our parasympathetic system is there to counteract this activation. This is a bit like a tug-of-war.

In the modern workplace, our sympathetic nervous system can be put into a hyperactivated state, which can mean we lose homeostasis and can end up spending too much time experiencing stress.

Factors that can contribute to this hyperactivated state include constant change, volatility, uncertainty, complexity, and ambiguity, not to mention constant interruptions, lack of social connection and an absence of a sense of belonging.

Over time this hyperactivated state can weaken the vagus nerve and its ability to ensure that the parasympathetic nervous system counteracts the sympathetic nervous system (the vagal brake is weakened).

Managing stress via Vagus Nerve Tone and Activity

The activity (or strength) of the vagus nerve is known as vagal tone and its effective functioning in regulating the heart is known as cardiac vagal control (CVC).

Higher CVC is associated with:

• Our ability to manage stress and our vulnerability to stress
• Enhancing your brain’s executive functioning, for example, emotional regulation, sustained attention, analytical thinking
• Self-control
• An increased amount of positive emotions
• Social engagement
• Improved physical and mental health including a greater sense of well-being
• It is even considered that higher CVC is associated with wiser reasoning and less biased judgments as it promotes a state in which we are more self-distanced (consider others) rather than being self-immersed (egocentric)

You can improve vagal tone and therefore stress management with the following practices.

• Breathing exercises
• Meditation
• Exposure to cold
• Sleep
• Physical Exercise — especially Yoga
• Connecting in-person with others
• Flow experiences
• Playing wind musical instruments (especially clarinet)
• Volunteering

Stressors

Stress is related to the effects of internal and external factors on our physical, mental and social well-being.

As presented earlier in this article; in stressful situations, physiological changes occur that prepare us to fight, flee or even freeze.

Here is a list of different stress factors*.

Biological Stress Factors

• Tiredness
• Malnutrition
• Digestion
• Dehydration
• Infection
• Chronic disease
• Pain
• Pregnancy
• Lack of sleep or jet-lag
• Lack of daytime recovery
• Over-training
• Physical workload
• Poor nutrition
• Stimulants like coffee
• Medication
• Alcohol / Drugs
• Temperature / humidity
• Noise
• Bright light during the evening
• Altitude

Psychological Stress Factors

• Excitement
• Fear
• Negative feelings
• State Anxiety
• Depression and other mental diseases
• Relationship problems
• Traumatic events
• Sorrow

Social Stress Factors

• The absence of social needs (sense of belonging, recognition, etc)
• Level of safety we feel in our surrounding environment
• Pressure to be responsible for something
• Giving a speech or presentation

Context specific — Work related stress

• Work overload
• Time pressure
• Work rhythm — lack of recovery
• Role ambiguity
• Lack of meaning and purpose in role
• Role conflict
• Siloed working — competition in place of collaboration
• Being responsible for others
• Under qualified — lack of competencies for role
• Overqualified — not challenged
• Lack of job security
• Poor relations with manager or colleagues — not feeling like you belong and lack of respect
• Lack of ability to delegate
• Lack of autonomy and ability to make decisions
• Office politics
• Lack of development opportunities
• Lack of a mentor or development partner

References:

*The above physical factors are validated by Firstbeat Technologies Ltd.

Work stressors reference: Michie S CAUSES AND MANAGEMENT OF STRESS AT WORK Occupational and Environmental Medicine 2002;59:67–72.