By Anna Kiesewetter
For most animals, stress comes in episodes. When an animal is in a life-or-death situation, its sympathetic nervous system is activated, which increases its heart rate as well as the energy supply available to it. The activation of the sympathetic nervous system also shuts down any unnecessary functions. This is what aids a deer in escaping a wolf pack. But what happens when we begin to perceive stress in a recurring fashion? What happens when our worries pervade our lives for days, weeks, and even months on end—what happens when we just can’t choose between fight or flight?
To provide a bit of context, we’ll start with a brief overview of the body’s reaction to stress in its most natural and intended form. Imagine that a deer notices a wolf trailing behind it. Once it detects this external stressor, the hypothalamus—a small region at the base of the brain—dispatches nerve and hormonal signals to the adrenal and pituitary glands. These glands then secrete an abundance of hormones such as epinephrine (also known as adrenaline) and cortisol. Epinephrine increases the body’s heart rate, blood pressure, and energy supplies, while cortisol enhances the usage of sugars in the bloodstream and shuts down nonessential functions like the immune, digestive, and reproductive systems. So, thanks to the deer’s sympathetic nervous system releasing these hormones, the deer now has the necessary energy and bodily focus to escape this life-or-death situation.
Now, let’s apply this situation to humans. Our stressors are not always so primitive, and many of them can even be internal; long-term stressors such as the fear of losing a job, a tumultuous relationship, or the pressure to succeed in school can, and will, slowly eat at us. And while this stress may benefit us in the short-term, it will eventually have negative impacts on our body. Essentially, if the stressor doesn’t go away, our hormone levels won’t return to normal. This will result in a buildup of cortisol levels in the body, which has a multitude of long-term negative effects.
Let’s take a look at the effects cortisol buildup can have on the cardiovascular system. In the short-term, cortisol can lead to a faster heartbeat, which helps pump blood and oxygen to the brain and to the limbs needed to address the stressor. In the long-term, however, this can lead to chronic hypertension and high blood pressure. It can even cause inflammation at bifurcation points—areas where blood vessels branch out. This can be particularly dangerous, as inflamed bifurcation points can become blocked by cholesterol and fat, leading to an increased likelihood of heart attacks and strokes.
Cortisol is also used to inhibit unnecessary systems. This is very beneficial during the fight-or-flight response, as resources are allocated from one system to another, depending on the threat. However, if the stressor continues to be detected for a prolonged period of time, as many work and school related stressors are, these inhibited systems’ capabilities can be greatly reduced, resulting in some very negative health effects. For example, cortisol blocks insulin production and secretion so that sugar can energize the bloodstream. This, however, can increase the likelihood of diabetes in the long-term. Furthermore, cortisol inhibits fat storage and the usage of estrogen, which is why serious dancers, runners, and athletes often have delayed puberty. Cortisol also impedes the immune system’s formation of B and T cells, which can not only make a person more susceptible to disease, but can also increase one’s immune response time. Too much cortisol can even lead to chronic conditions such as Cushing’s syndrome, the effects of which include rapid weight gain in the face, chest, and abdomen, hypertension, osteoporosis, muscle weakness, excess facial hair, and irregular periods in women.
Even more daunting are the intergenerational effects of increased cortisol levels. Women who were pregnant during the Dutch Hunger Famine of 1944-1945 had increased cortisol in their bloodstream. This increased level of cortisol created something called a metabolic imprint, which essentially sent a signal to the fetus that told it that its environment was stressful, and therefore required increased cortisol secretion. As a result, many of those born directly after the famine not only developed obesity, but also had higher mortality rates. A traumatic childhood can also cause stress dwarfism, a condition which can result in permanently stunted growth. For instance, in a Field and Crew experiment, certain babies were physically touched and held by their parents while the others were neglected. The absence of touch was actually a stressor for the infants, and reduced their growth by 50% compared to the touched children.
Now, it’s obvious that there are many scary aftereffects of chronic stress. And because of that, it’s important that we know how to combat it. To reduce cortisol levels, getting between 7-9 hours of sleep per night with a continuous sleep schedule is recommended. Exercising in moderation also fights stress, although overexertion can produce cortisol. Practicing mindfulness and writing about your stress has also been shown to reduce cortisol levels. Finally, eating healthy helps as well. Foods with sugar and caffeine tend to increase cortisol, while dark chocolate, fruits, black and green tea, probiotics, and water help to reduce levels.
Overall, chronic stress produces many adverse effects in humans, which we don’t see very often in other animals. Recognizing the continuous nature of human stressors is crucial in finding ways to reduce stress.
What Did You Learn?
1. What is cortisol? In what ways is it both beneficial and detrimental for the human body?
Cortisol is a steroid hormone in the glucocorticoid class of hormones. It is used in the sympathetic nervous system to inhibit unnecessary bodily functions and enhance the usage of sugars in response to a stressor. In the short term, this inhibition gives the body the energy to evade or fight threats, giving us an increased chance of survival or the energy to complete the last leg of our track race. However, cortisol can cause long-term conditions like hypertension, diabetes, and Cushing’s syndrome when built up over time by impeding the regular function of the immune, reproductive, and digestive systems.
2. How can we combat chronic stress?
A stable nighttime sleep schedule, exercising in moderation, practicing mindfulness, cultivating healthy relationships, and consuming a healthy diet low in sugar and caffeine can all help to diminish cortisol levels and thereby reduce stress.