Short bursts of stress are a normal part of life. A deadline, a near-miss in traffic or a tough conversation can all set off the body's stress response, which then settles back down. Problems arise when that response stays switched on for weeks, months or years.

This explainer covers how the stress response works, why chronic stress is harmful, and what it can do to the heart.

Key Points

• Stress triggers the release of hormones like adrenaline and cortisol that prepare the body to react.
• When stress becomes constant, those hormones stay elevated and can disrupt nearly every system in the body.
• Chronic stress can raise blood pressure, heart rate, blood sugar and cholesterol.
• Stress also drives habits — smoking, overeating, inactivity — that increase heart disease risk.

What Stress Is

Stress is the body's biological response to demanding situations. It's designed to protect us: when a threat appears, the body releases hormones such as cortisol and adrenaline, raising heart rate and breathing to create a state of heightened alertness — the classic "fight or flight" response. In the short term, this can even sharpen performance.

How the Stress Response Works

When you perceive a threat — a large dog barking on a morning walk, or an unexpected noise in the middle of the night — a small region at the base of the brain called the hypothalamus sets off an alarm. Through nerve and hormonal signals, it prompts the adrenal glands to release a surge of hormones.

Adrenaline increases heart rate, raises blood pressure and boosts energy. Cortisol, the primary stress hormone, increases sugar in the bloodstream, helps the brain use that glucose and makes tissue-repair substances more available.

Cortisol also dials down functions that aren't essential in an emergency. It alters immune responses and suppresses digestion, reproduction and growth. The system also communicates with brain regions that control mood, motivation and fear.

Once the threat passes, hormone levels fall, and heart rate, blood pressure and other systems return to normal. But when stressors never let up, the fight-or-flight response stays on.

Why Chronic Stress Is Harmful

Physical threats are rare for most people, but psychological pressures — big projects at work, bills, caring for family — show up every day. The body responds to these much as it would to a barking dog, except the "threat" doesn't go away.

Long-term activation of the stress system and prolonged exposure to cortisol can disrupt almost every process in the body, contributing to weight changes, headaches, depression, sleep problems and strain on the heart.

Acute vs. chronic stress

Acute stress is short-term — for example, long hours to finish a project on a tight deadline. Once it's done, the body can recover.

Chronic stress is ongoing, such as persistent financial pressure. Constant overtime, frequent travel and high-pressure work relationships can keep the body in a heightened state even at home, adding wear and tear that may contribute to heart disease.

How Chronic Stress Affects the Heart

Ongoing stress can raise blood pressure, cholesterol, blood sugar and heart rate. When these remain elevated for long periods, the heart is under added strain.

Stress also influences behavior. Some people turn to alcohol or cigarettes to cope, and stress can lead to inactivity and overeating. Those habits can raise blood pressure and damage artery walls, compounding the problem. Understanding where your heart stands — for example, with a coronary calcium scan — can help put stress-related risk in context.

Effects Throughout the Body

Chronic stress can drain energy, disturb sleep and leave people irritable, forgetful or feeling out of control. Symptoms vary widely from person to person. Over time, it can contribute to a range of physical and mental health problems, including:

• Anxiety and depression
• High blood pressure and heart disease
• Sleep problems
• Digestive issues
• Headaches
• Weight gain
• Problems with memory and concentration

Taking Action

Managing stress — through regular exercise, sleep, social connection and, when needed, professional support — benefits both mind and body. It's also worth discussing any concerns with a health care provider. For people who want a clearer picture of their cardiovascular health, preventive scans are one option to consider alongside regular care, and the Advanced Body Scan FAQ explains how they work.