The Biology Of Stress At Work

Elvir Muhic

Written by

Ajla Vejzović

Imagine a giant mammoth is chasing you, and you have to find a way to survive. The cascade of biological reactions that follows is what science defines as acute stress in the body. For our ancestors, it served them well; killing or fleeing from a mammoth was a perfectly good way to end a stress episode.

Today, however, there are no mammoths. A long email, a deadline, or a toxic atmosphere can be enough to trigger stress, but without the time or the way to “shake it off” in that moment.

In this article, we’ll walk through the biology of workplace stress and what science recommends for prevention and management.

What is stress?

Stress can be defined in several ways, depending on the angle from which it is viewed. Here are three widely cited definitions:

According to the World Health Organization (WHO): Stress is a state of worry or mental tension caused by a difficult situation. It is a natural human response that prompts us to address challenges and threats in our lives.

According to the American Psychological Association (APA): Stress is a physiological or psychological response to internal or external stressors, involving changes that affect nearly every system of the body, influencing how people feel and behave.

According to Hans Selye, the scientist considered the father of modern stress research, Stress is the non-specific response of the body to any demand placed upon it, regardless of whether that demand is mental or physical in nature.

Employee under pressure - reasons for high cortisol.

Source: Pexels

What happens in the body during the stress response?

The stress response is one of the oldest biological mechanisms in existence. When the perception of a threat reaches the brain, a precisely coordinated chain of reactions is triggered, involving the nervous system, hormones, and nearly every organ in the body.

Meet the amygdala, a small, almond-shaped part of the brain also known as the emotional chip. Its job is singular: to detect a threat and react. When the amygdala receives a danger signal, whether a sound, an image, or a negative email, it immediately activates the hypothalamus.

Think of the hypothalamus as a command center. It sends a signal to the autonomic nervous system, triggering the fight-or-flight response, in which the heart accelerates, blood vessels constrict, muscles receive more blood, and breathing speeds up.

Cortisol and the stress response

First, let’s clear something up: cortisol is not the villain. It is called the “stress hormone” because the body releases it during the stress response. In reality, cortisol is involved in glucose metabolism, meaning it helps the body utilize and distribute glucose as a source of energy.

Specifically, cortisol:

increases blood sugar levels
improves glucose utilization in the brain
increases the availability of substances that repair tissue.

It also slows down functions that would be unnecessary or harmful in a fight-or-flight situation, altering immune responses and temporarily suppressing the digestive system, reproductive system, and growth processes.

In short, cortisol helps your body deal with stressful situations and return the organism to a resting state as quickly as possible.

The three phases of the stress response

According to Selye’s model, there are three phases of the stress response.

Phase 1

Phase 2

Phase 3

Alarm: adrenaline and cortisol are released, and the body mobilizes all its resources.

Resistance: the body has adapted and is trying to maintain balance under pressure. Resources are being depleted.

Exhaustion: the system breaks down. Immunity drops, fatigue becomes chronic, and emotional reserves are empty.

This third phase is what is today described as burnout syndrome.

Acute vs. chronic stress

Acute stress is a short-term, intense reaction of the body to a specific threat or challenge. It appears quickly, lasts briefly, and disappears once the situation passes. At work, this might look like a presentation in front of a client, an unexpected call from the boss, or a system crash right before a deadline. The body reacts, does its job, and returns to normal.

Chronic stress occurs when the stressor does not go away, but repeats or persists over an extended period of time. The body never receives the signal that the danger has passed, so it remains in a state of constant alertness, which over time begins to affect health.
Science describes this through the concept of allostatic load the accumulated wear and tear on the body resulting from a prolonged stress response.

At work, causes of chronic stress can include unrealistic deadlines that keep replacing one another, unclear instructions from management, the feeling that work is never truly done, emails arriving at 10 pm, and a toxic team atmosphere that drags on for months.

Impact of chronic stress on body - Zen2Fit Corporate Wellness

Source: Freepik

The impact of chronic stress on the body

Brain and memory – the hippocampus is particularly vulnerable to prolonged stress. Studies using various brain imaging methods have shown a reduction in hippocampal volume, which is directly linked to memory deficits. In practical terms, this means it becomes harder to concentrate and creativity declines.

Heart and inflammation – research published in Antioxidants & Redox Signaling shows that both chronic and acute psychosocial stress trigger systemic inflammation through neuroimmune interactions and accelerate the development of atherosclerosis.

Sleep – elevated cortisol suppresses melatonin and blocks adenosine, the molecule responsible for sleep pressure. The result: heightened alertness before bedtime, insomnia, fragmented sleep, and the inability to reach the deep, restorative sleep the body needs.

FREQUENTLY ASKED QUESTIONS

What are the first signs of burnout in employees? The early signs to watch for include chronic fatigue that does not improve even after rest, a decline in work quality and an increase in errors, social withdrawal and reduced communication with the team, emotional reactivity to small things that previously were not an issue, and growing cynicism and loss of motivation toward work.

What can a company concretely do to reduce stress in the team? The most concrete step a manager or HR professional can take is engaging a corporate wellness platform or team that simultaneously addresses all three aspects of wellbeing. This holistic approach, unlike one-off workshops or isolated benefits, builds systemic stress resilience within the team, which directly impacts productivity, employee satisfaction, and turnover rates.

Can work-related stress be grounds for sick leave in Bosnia and Herzegovina? Yes, but not directly under the label of “stress.” Bosnia and Herzegovina, as a WHO member state, has included burnout on its list of disease codes. However, practice varies from canton to canton in some parts of BiH, sick leave cannot be opened directly under that code, but rather under related diagnoses.