What Is Stress? Definition, Causes, and How It Affects the Body

Stress is a biological response to perceived challenges or threats. It activates the nervous and hormonal systems — preparing the body for action through adrenaline and cortisol.

This reaction helps us cope with short-term challenges, but if it continues too long, it can damage health and performance.

In this article, you'll learn what stress is, what causes it, and how it affects your body — especially in the workplace.

What Is Stress? A Simple Definition

Stress is the body’s natural response to any demand or challenge, activating systems that prepare you to take action — often called the “fight-or-flight” response.

Stress is not a disease — it’s a physiological response. When you experience a challenge (called a stressor), your body shifts into a state of alert to help you respond. This survival response is designed to protect you — but it can also harm you if it goes on too long.

Stress activates both the nervous system and hormonal system. Hormones like adrenaline and cortisol raise your heart rate, sharpen your focus, and prepare your muscles for action — the classic “fight-or-flight” response.

This was incredibly helpful for our ancestors facing physical threats. But today, even psychological or emotional challenges — like deadlines, emails, or financial worries — can activate the same system.

Cortisol, often called the “stress hormone,” helps regulate energy, focus, and metabolism during stress. But prolonged high cortisol levels — common in chronic stress — can lead to fatigue, anxiety, weight gain, and immune dysfunction.

Here’s an infographic that explains what stress is, how it affects you, and why managing it matters. 

Common Causes of Stress at Work and in Life

Stress looks different for everyone, but certain common stressors affect large numbers of people.

General Life Stressors:

• Financial problems
• Health issues
• Divorce or relationship tension
• Academic pressure

Workplace Stressors:

• Excessive workload or unrealistic deadlines
• Lack of control over tasks or decisions
• Poor communication or unclear expectations
• Micromanagement, toxic leadership, or harassment
• Job insecurity or fear of layoffs

These factors don’t just affect your mood — they trigger a biological stress response, and when repeated, they can lead to chronic stress and long-term health issues.

Is Stress Always Bad? Understanding Acute Stress

Not all stress is harmful. Acute stress — the kind you feel before a speech or tight deadline — can be helpful.

It boosts:

• Focus
• Energy
• Motivation

This form of stress fades once the challenge passes. It’s a short burst of physiological energy that can help you perform at your best.

Symptoms of Chronic Stress

Chronic stress happens when stressors continue over time without relief. Your body stays in high-alert mode, which begins to damage your health.

Physical symptoms:

• Headaches or migraines
• Sleep disturbances
• Muscle tension
• High blood pressure
• Digestive problems
• Reduced libido

Emotional & mental symptoms:

• Irritability or anxiety
• Difficulty concentrating
• Low mood or motivation
• Feeling overwhelmed
• Depression or helplessness

These symptoms result from the prolonged activation of stress hormones like cortisol and noradrenaline. You can read more about how your body reacts to stress in this full breakdown of stress symptoms. 

👉 Read about 10 early signs of burnout at work

What Is Stress Overload? Warning Signs

If multiple stressors pile up without recovery, your system can go into overload.

This can lead to:

• Burnout
• Social withdrawal
• Constant worry
• Substance misuse
• Disordered eating
• Exhaustion and poor immune function

Stress overload can resemble anxiety — but while anxiety often stems from internal fears, chronic stress is usually triggered by external demands. Understanding the difference is important when choosing how to respond.

How to Deal with Stress: First Steps

The most important thing is to act early. Ignoring stress symptoms usually makes them worse.

Start here:

• Identify your personal stressors (especially at work)
• Build stress recovery into your week (like movement, rest, or time off)
• Talk to someone — a coach, trusted friend, or mental health professional
• Use evidence-based tools (like CBT, mindfulness, or structured planning)

From Awareness to Action: Resources for Change

You’ve just taken the first step by learning what stress is and where it comes from. If workplace stress is affecting your performance, health, or relationships, don’t wait until it becomes unmanageable.

Explore more articles on workplace stress at stressinsight.com
Check out our course Surmounting Stress for a science-based path to stress relief

Frequently Asked Questions About Stress

Q: What are the most common causes of stress at work?
A: Common workplace stressors include excessive workload, unclear expectations, poor leadership, and lack of control.

Q: What are examples of stress in daily life?
A: Financial issues, job pressure, relationship conflicts, and health problems are all common life stressors.

Q: Is stress always bad?
A: No — short-term stress can be beneficial. It becomes a problem when it is intense, frequent, or long-lasting.

Q: What’s the difference between chronic stress and anxiety?
A: Chronic stress usually stems from external pressures. Anxiety often involves internal worries and is classified as a mental health disorder.

Q: What are the first signs of burnout?
A: Emotional exhaustion, reduced performance, and a sense of detachment are early signs of burnout, often linked to ongoing work-related stress.

Q: How does stress affect the body?
A: Stress activates the nervous and hormonal systems, increasing heart rate, muscle tension, and alertness. Chronic stress can lead to headaches, sleep problems, high blood pressure, and fatigue.