“Stress” is a common feeling people experience when trying to cope with undesirable or demanding situations. The stress response triggers a protective mechanism against the perceived or actual danger. Stress is often associated with a negative impact on performance and quality of life; however, a healthy amount of it can keep us motivated and improve stamina.
Acute stress lasts only for a short period of time, usually hours to a few days. Many of us might relate to the stress experienced when studying for final exams or during an argument with a loved one. When stress persists for more than a few days, it is called chronic stress. Examples of chronic stress include unemployment or financial duress, persistent issues with a boss, coworker, friend, or significant other, or injury that results in significant and long-lasting injury. Chronic stress may significantly affect physical and mental health.
Stress is usually categorized into three stages: alarm, adaptation, and exhaustion or recovery. Each stage is detailed separately below.
Alarm: Otherwise known as the “fight-or-flight response,” the alarm stage enables us to face the danger (or run away!). “Fighting” involves the release of adrenaline and cortisol, increasing heart rate and blood pressure, blood sugar, and alertness. Although traditionally a survival mechanism, this response still regulates our nervous system in times of stress. If the trigger goes away quickly, our body returns to its normal resting state with few lasting effects.
Adaptation: If the stressful situation persists, the body uses all of its resources in order to adapt to the stress. This involves continuous release of stress hormones and persistently elevated heart rate, blood pressure, and blood sugar. The result of elevated cortisol and adrenaline can be issues sleeping, irritability, increased or decreased appetite, and difficulty concentrating.
Exhaustion OR Recovery: If the stress is successfully overcome, the body will start to recover. However, if the body has used up all its resources and the stressor persists, it leads to the exhaustion stage. At this point, the body will try to shut off unnecessary activities in an effort to conserve energy. This can lead to indigestion, immune system suppression, weight gain, and fatigue.
Digestive Issues: As part of the stress response to perceived or actual danger, bodily functions are directed away from “unnecessary” activities such as digestion to fuel the heart, lungs, and brain. Indigestion, acid reflux, diarrhea, or constipation may result. When stress persists for a prolonged period of time, the gut lining may become irritated and inflamed, leading to ulcers.
Infections: Whenever a pathogen enters the body, immune cells release chemicals called cytokines. Cytokines lead to the direct killing of the pathogen, along with production of antibodies against the pathogen. The hormone cortisol suppresses the release of cytokines, which in turn suppresses the immune system. This can cause increased susceptibility to colds, the flu, and other infections.
Poor Glycemic Control: Cortisol causes the liver to synthesize glucose via glycogenolysis (breakdown of glycogen) or gluconeogenesis (conversion of fatty acids or amino acids into glucose). Cortisol also inhibits the action of insulin, preventing glucose from being taken up and stored in cells. Together, these actions of cortisol increase blood sugar and promote insulin resistance, increasing the risk of diabetes and other metabolic syndromes.
High Blood Pressure: Adrenaline constricts blood vessels and increases heart rate, resulting in increased blood pressure. In turn, the heart experiences increased cardiac output, which essentially causes the heart to work harder to pump an equal volume of blood. This can cause damage to heart muscle, which can increase the risk of coronary heart disease or heart failure. High blood pressure also damages the walls of the blood vessels, which can trigger the formation of clots that can cause heart attacks or strokes.
Obesity: Cortisol causes breakdown of stored fats and relocation of fats to the abdominal region. Cortisol also prevents glucose uptake from cells, making them starved of energy. This causes increased hunger and cravings for high-calorie foods, leading to weight gain.