stress-interferenceTaking a final exam can be a stressful experience for any student. As the moment arrives when the tests are handed out and procrastination is no longer an option, nervous attentiveness and the flushed pallor that accompanies an increased heart rate can clearly be observed in some students. How do stress and anxiety affect a student’s performance on exams? Does stress affect a student’s ability to learn?

Introduction
Taking a final exam can be a stressful experience for any student. As the moment arrives when the tests are handed out and procrastination is no longer an option, nervous attentiveness and the flushed pallor that accompanies an increased heart rate can clearly be observed in some students. What is it about the exam that is stressful, and why don’t all students respond to the exam in the same way? What effect will this stress have on a student’s performance? In order to understand the answers to these questions, we must understand a little more about what stress is and how it affects both the brain and body.

…studying biological stress is like studying the wind from within an enclosed building. If you are not able to measure it directly, you have to infer its presence by studying how objects like trees move in response to it.

The study of the biology of stress came into being in the 1930’s when a medical doctor by the name of Hans Selye decided to examine the body’s general response to being sick. Selye differed from most doctors of his day in that he did not focus on the symptoms that were unique to a given illness. Instead, he explored the similarities found in all illnesses. In effect, he uncovered a general way that the body adapts to changes in its internal or external environment. Selye discovered the biological response to what we now call stress. (For more on Hans Selye, see his profile on BrainConnection.com.)

Biological stress is difficult to study in and of itself because what constitutes a stressful situation can, to some extent, be different for each individual. Public speaking, for example, may be stressful to some, while to others, it is a daily vocation that causes no serious physical or emotional consequences. In this sense, studying biological stress is like studying the wind from within an enclosed building. If you are not able to measure it directly, you have to infer its presence by studying how objects like trees move in response to it. Luckily, the internal reactions that a body goes through in response to stress are similar and consistent in all of us. This gives scientists a means with which to study the effect of stress on the body. This teleological reasoning produces a definition of stress as anything that triggers a “stress response” in the body.

The Body’s “Stress Response”
In order to better understand how stress affects our lives, let’s examine how our bodies respond to a stressful event. Say for example you’re crossing the street and suddenly a speeding car appears from nowhere barreling towards you. Slamming on the breaks, the car skids to a stop inches from where you are standing. If this were to happen to you, your brain would immediately respond by marshaling not one, but two, coordinated stress responses. The first response is fast, the second is slower. Each response serves an important purpose. The fast response is designed to help you survive the immediate threat; the slow response helps you repair any damage the threat may have caused your body.

The Fast Response
The fast response starts simultaneously with perception of the threat. As soon as your brain registers a threat—in many cases even before you consciously have a chance to identify what the threat is—it sends signals throughout the body to prepare your defense. It is as if the body’s electricity switch has been turned on. Within seconds, your muscles are primed for movement and your body is ready to run or jump back out of the path of the speeding car. Signals, automatic reactions coming from deep within the brain, take over in order to ensure that one thing happens— you survive the threat at hand.

Receiving alert signals from the brain, the sympathetic nerves signal most of the organs of the body, activating the ones necessary for survival and inhibiting or quieting those that are not needed. The adrenals flood the blood with the hormone adrenaline. Adrenaline speeds up the heart rate so that the heart can pump out more oxygen-rich blood to the muscles. Adrenaline also works together with the sympathetic nerves at the blood vessels, changing the pattern of blood flow to shift the supply of freshly oxygenated blood away from the non-essential organs involved in functions like digestion and reproduction to the muscles that need to respond to the threat. Within the brain itself, neural pathways involved in increased attention and focus are activated.

The result of this call to arms is that within seconds, every system of the body is quickly tuned to one purpose: avoiding the threat that is about to take your life! Known as the fight or flight response, this process is evolutionarily designed to increase the chances of surviving sudden unexpected threats. You can imagine that when we were still hunting for a living—and being hunted ourselves—the speed of this response could make the difference between life and death.

Nowadays, activation of this quick response is observed only on a periodic basis, however, remnants of it can sometimes be seen when something sudden and unexpected happens. In general, scheduled exams do not elicit this type of fight or flight response, although remnants of it may be seen in a classroom immediately following the surprise announcement of a pop quiz.

The Slow Response
Accompanying this fight or flight reaction is a slower response. It is this slow response that may have a more important impact on both our classroom performance and daily lives. When the car threat first appeared, a second signal was sent from the brain to a small gland, called the pituitary, which hangs directly below the center of the brain. During stressful events, the pituitary secretes a peptide called adrenocorticotrophin or ACTH, into the blood. ACTH travels through the blood to the adrenal, where it signals the production of a hormone called cortisol. Cortisol aids the body in recovering from the detrimental effects of acute stressful experiences.

Even non life-threatening stresses, such as worrying over an exam, can work to produce small but significant elevations in the body’s cortisol levels. After enough of these small increases, the body soon resets its control mechanism to maintain a higher constant amount of cortisol in the body.

Cortisol helps the body manage stress by freeing up energy stores. It works in the liver to release sugar into the blood. It also signals the body to release fat and muscle stores so that the body can utilize the energy in them. The logic behind the slower stress response is that the quick fight or flight response uses up a lot of the body’s available energy. The slower response helps replenish the available energy. After all, if you survived the threat from a predator (or bad driver), you might be hurt or unable to find food and need more energy to help speed your recovery. Unlike the fast response, which happens within seconds, the whole process from stress onset to increased cortisol can take from one to five minutes. Unlike adrenaline, which is stored ready for use in the adrenal, cortisol must be synthesized from scratch by the adrenal every time more of it is needed. This synthesis takes time making the cortisol response a slower process.

The body usually has some small amount of cortisol circulating in the blood at all times. Following stress, however, this level is increased. The brain will turn off the pituitary signal to produce more cortisol if it senses there is enough circulating in the blood already. The fact that cortisol works both in the body and in the brain to turn off its own production sets up a feedback loop between the brain and body. This loop works kind of like the thermostat in your house. The thermostat signals the furnace to heat up the house, just as the brain signals the body to produce cortisol. Once a certain temperature is reached, the thermostat turns off the furnace; when high enough cortisol levels are reached in the body, the brain will turn off cortisol production.

The problem is if somebody comes in from the cold and wants to get warm quickly, they immediately turn up the thermostat, which raises the temperature of the house to a new level. If enough cold people come in and crank up the thermostat, soon the house is overheated. In this analogy, the people turning up the thermostat in our house are the equivalent to minor stressful events turning up the cortisol production signal in the brain. Even non life-threatening stresses, such as worrying over an exam, can work to produce small but significant elevations in the body’s cortisol levels. After enough of these small increases, the body soon resets its control mechanism to maintain a higher constant amount of cortisol in the body.

Chronic elevations in cortisol can have long-term health effects. Heart disease, ulcers, insulin resistance, and hypertension have all been associated with high levels of cortisol.

Stress in the Classroom
Our modern life has liberated most of us from facing life-threatening situations on a daily basis. We have, however, replaced these threats with events that we perceive, or react to – with the same high levels of cortisol response. Exams, social situations, performance reviews, and calls into the boss’s office have replaced the evasion of predators as the main activators of our biological stress system.

In the classroom, any positive priming effects of stress on learning may be even harder to observe… There is no guarantee that any positive effects of stress on learning will outweigh the negative cost of too much stress on our bodies.

Every time stress hormones increase, the brain senses the change with a cadre of receptors that detect cortisol and other stress-related hormones. Interestingly enough, these receptors, which are found throughout the brain, are concentrated the highest in the hippocampus, a brain area involved in memory formation and spatial awareness. This makes theoretical sense when we think of stress as a response to a threat against our lives, such as a predator. After surviving, the slower cortisol response primes the memory circuits in the brain to help you remember where you were and what the environmental situations were surrounding the attack. Remembering this type of information helps you avoid a similar situation in the future.

The effect of stress on memory, however, makes less sense when we consider our modern situation. Nowadays, the cortisol response is activated in anticipation of pending events, such as exams or uncomfortable social situations, instead of as a result of such events. Memory priming advantages are not as clear in such a backwards situation where the stress response precedes the actual event. Effects of stress hormones on memory have been observed in rats performing water maze tasks that test how well the animal can recall a particular spatial position in a tank of milky water. These effects however are subtle and may not even be noticed if not for the detailed reaction times measured in such tests.

In the classroom, any positive priming effects of stress on learning may be even harder to observe. How we encode things in memory is still not clearly understood. There is no guarantee that any positive effects of stress on learning will outweigh the negative cost of too much stress on our bodies. It is also not clear that the effects of stress on one type of spatial memory task will translate to gains in other areas of learning, such as math or English.

What is clear is that what constitutes stress is determined by individual perceptions. How much control a person feels in a particular situation dramatically effects how much of a stress response his or her body produces. Keeping that in mind, the answer to performance seems to lie in keeping a healthy balance between not responding and over responding to the challenges and tests our lives present us with.