Many people think stress is an outside force that causes them to feel tension. That's not stress, though--it's a "stressor." Stress is the feeling that can result from a stressor. This may seem like a trivial distinction, but it's vitally important. It means that if you don't perceive a stressor to be stressful, then it's not one. Some researchers define stress as any difficult situation that you can't control.
If you can control a difficult situation, it will probably be good for your brain. It will coax your brain to make new synaptic connections between neurons, as you attempt to resolve the situation....
But if you perceive your situation as out of your control, you will be much less likely to engage these neurons in creative problem solving, and much more apt to secrete the hormones that will "cook" your brain.
The primary factor in determining job stress, most experts agree, is a person's degree of control over the work situation. If people are free to make their own decisions, they feel much less stress on the job than people who must constantly defer to others. Therefore, jobs that have high demands, but also high degrees of authority, are actually less stressful than jobs with fewer demands but less authority Thus, being a nurse is often more stressful than being a doctor....
People who have the least sense of control--and the highest levels of stress--are often those who have a personality trait called "learned helplessness."
Here is what happens when you activate your stress response:
1. You release adrenaline, causing your blood sugar to rise, your blood pressure to increase, your heartbeat to accelerate, your arteries to constrict, and your digestion to slow. For a limited time, your mind and muscles work efficiently.
2. If the stressor is severe, or persists for more than just a couple of minutes, you also secrete cortisol. This "locks in" a long-lasting stress response.
A small amount of stress, over a very short period, is healthy. It causes a mild degree of excitation, and helps people to become involved in productive activity. This healthy level of stress, sometimes called eustress, actually helps prevent unhealthy levels of stress. When you have absolutely no stress, you soon become bored, and then boredom itself causes unhealthy stress of levels.
Further, a very mild degree of stress, at intermittent moments, is good for our brain. It causes you to release norepinephrine, the excitatory neurotransmitter. You need norepinephrine to move hour short-term memories to long-term storage. You also need it to help give you a positive mood.
Therefore, your key to successful stress management is to keep just a mild, healthy degree of stress in your life. Your stressors will then feel like challenges, not problems. Then, when you meet those challenges, your brain will engage in creative thinking, grow new dendrites, and make new synaptic connections.
Unhealthy levels of stress occur primarily when you feel as if your ability to deal with your stressors is inadequate. That creates the nerve-racking, depressing, annoyed feeling that we all identify as stress.
If you experience unhealthy levels of stress only very occasionally, it will do little damage. But if you experience prolonged, high-level stress on a daily basis, it will profoundly disturb your physical, intellectual, and emotional health. If you do experience this type of chronic, uncontrolled stress, you will soon become a victim of one of life's most damaging phenomena, the "general adaptation syndrome." Watch out for this syndrome! It can "cook your brain."
In 1956, the endocrinologist Hans Selye became one of the pre-eminent pioneers of stress research, when he wrote the first major book on the damage that stress does to the body. In that book, The Stress of Life, Selye described how stress gradually assaults the body, through a mechanism that he called the "general adaptation syndrome," which is the broad set of changes your body goes through when it is chronically subjected to the stress response.
There are three stages to this set of changes. The first is the "alarm reaction," when you secrete adrenaline and cortisol, causing your entire body and mind to spring into action against the stressor. The second stage is the "stage of resistance," in which your mind and body try to pinpoint the threat, and activate only the most appropriate resistance mechanisms. During this phase, the secretion of adrenaline and cortisol decreases, while the "battle" against the stressor is fought only by the most appropriate organs or systems. Then, however, comes the most insidious phase: the "phase of exhaustion."
During the phase of exhaustion, the specific, appropriate organs or systems that are "fighting" the stressor wear out, and become depleted. Your mind and body then "draft" other organs and systems to "join the battle." When this happens, there is again a surge in the secretion of adrenaline and cortisol.
During the exhaustion phase, most of the organs and systems in your body are affected, and some are badly harmed. Often there is substantial enlargement of the cortex of your adrenal glands. There is also often a shrinkage of your thymus, spleen, and lymph nodes. There is generally a decrease in the number of your immune system's white blood cells. Excess stomach acid is secreted. As a rule your blood pressure increases. Your sex hormones almost always decline.
Of course, when these changes occur, illness often follows. It's common for people who suffer from the general adaptation syndrome to have chronic high blood pressure. It's also common for them to develop minor illnesses. Sometimes, high levels of chronic stress can even contribute to catastrophic illnesses, including heart disease and cancer.
Mortality and illness among the chronically stressed rises sharply. For example, an older person who has lost a spouse is ten times more likely to die within one year of this loss than an older person whose spouse is still alive. Similarly, when a person gets divorced, his or her probability of significant illness over the next year increases by 1,200 percent.
Even recovery from injury is hampered by chronic stress. In one recent study, skin wounds among highly stressed subjects took an average of forty-nine days to heal completely, while skin wounds among non-stressed subjects took only thirty-nine days to heal. Research even indicates that stress can significantly increase levels of "bad" LDL cholesterol.
It's not only the body that suffers from stress, though. The brain does, too. When the exhaustion phase of chronic stress hits, learning ability and concentration nosedive, partly because of the effects of cortisol. In one revealing study, students with high levels of chronic stress scored 13 percent lower on IQ tests than students with low stress.
High blood pressure caused by chronic stress also reduces cognitive function. As I've already shown, "What's good for the heart is good for the head." And few things are worse for the heart (and the head) than high blood pressure.
In addition, the exhaustion phase of the general adaptation syndrome causes a deficit of the important neurotransmitter norepinephrine--particularly in the frontal love of your neocortex, where much of your abstract thinking takes place.
Chronic stress causes norepinephrine to be shunted away from your limbic system. As you'll recall, your limbic system controls your emotions. Because of this lack of norepinephrine in the emotional center of your brain, chronic stress can cause you to experience biological depression, anxiety, and malaise. If your chronic sress lasts long enough, it can even biochemically create anhedonia--the inability to feel any emotional pleasure.
Another unwanted mental effect of chronic stress is its influence on brain waves. A person experiencing stress has a predominance of "uptight" beta waves, rather than "calm" alpha and theta waves. Beta waves are also less conducive to learning and concentration than alpha or theta waves.
Finally--and most harmful of all--chronic stress creates oversecretion of coritsol. And cortisol, as mentioned previously, wages a "three-stroke attack" on your brain: It starves the brain of its only energy source, glucose; it interferes with neurotransmitter function; and it leads to the eventual death of brain cells.
Another tragic consequence of unrelenting stress is its assault on the mechanism that naturally shuts off your cortisol production. This cortisol shut-off usually occurs when the threats against you have passed. When your limbic system's hippocampus is healthy, it has the ability to give your endocrine system "feedback," and tell it when to quit producing cortisol.
But when your hippocampus becomes damaged by chronic stress, this feedback turns into the destructive "feedforward mechanism." The feedforward mechanism keeps demanding that you secrete more and more cortisol, even when you no longer need it. This unfortunate phenomenon is especially common in older people, whose hippocampi have been compromised by many years of stress. When the feedforward mechanism occurs, a degenerative cycle is created.
As you can see, chronic stress is a killer. It kills the body, the intellect, and the emotions.