The “fight or flight” response involves a complex series of reactions between mind and body. This is a normal and essential process, to a point. For our ancestors, the stressors were largely physical, such as the daily challenge to survive. The relatively brief surges in the body’s metabolism were necessary to hunt, fight, evade a predator or seek shelter.

In contrast, modern stressors are typically emotional, be they positive (preparing for big event) or negative (e.g., bereavement, divorce, financial insecurities). As such, they tend to be chronic, causing a continued stress response that can impact on cardiovascular health either directly or indirectly.

The stress response includes a number of physical changes that can affect cardiovascular health, including:

• A faster heartbeat can make the person vulnerable to certain types of chest pain (angina) and abnormal heart rhythms (arrhythmias).
  
  
• Stickier or thicker blood due to greater clotting ability can raise the risk of blood clots.
  
  
• Cardiac ischemia (a condition in which the heart does not get enough blood) is sometimes seen in response to stress, because stress causes the blood vessels to constrict abruptly. This decreases the blood flow to the heart, which over time can significantly increase the risk of death from a cardiovascular event.
  
  
• Glucose and fatty acids are converted to cholesterol if not used as energy during the stress response. This can promote hardening of the arteries (atherosclerosis). The process of atherosclerosis may also be hastened by frequent increases in blood pressure, which can thicken the walls of the blood vessels. As a result, stress has been linked with an increased risk of heart attack and stroke.
  
  
• The sustained presence of stress hormones keeps the body in a state of tension, which can weaken the cardiovascular system over time and increase the likelihood of developing high blood pressure (hypertension).

In addition, chronic stress has been linked to a condition called insulin resistance syndrome. This syndrome is characterized by an inability to convert food into usable energy and, consequently, seems to interfere with the body’s ability to dissolve blood clots. As a result, the body is more at risk for heart disease and other cardiovascular conditions.

People with driven or overcommitted personalities may have chronic stress and, therefore, may be at greater risk. Over time, this chronic stress may come to feel “normal” to some people, but the body is under stress all the same.

Researchers have recently discovered that some people can experience stress without realizing it. Participants in a study took a mental test designed to increase their stress level. Some of the participants did not report feeling stressed, and their pulse level remained the same. However, their blood pressure increased significantly, and researchers found they had a six-fold increase in the risk of heart attack or other severe coronary event.