We left off in the last article talking about the effects and management of acute stress reactions. This month, let’s talk about chronic stress states and the impacts they have on performance in the cockpit and on life and health in general. Think about chronic exposure to stress the same way you would think about repeated wear and tear stresses on an airplane. It’s not good and sooner or later something is going to snap. 
As with most things in life, stress is something that should be taken in moderation. Generally, we perform most reliably under manageable levels of workload stress that do not change suddenly and unpredictably. Some degree of stress is desirable as it primes the brain for peak performance to manage complex tasks. When there is no stress or stimulation the tendency is to be dulled into complacency. At the other end of the spectrum, too much stress overwhelms decision-making skills and the capability to manage emergencies. There is a definite inverted U-shaped curve for acceptable stress levels and the shape of this curve is different for everyone. For maximum safety and cockpit performance, each of us has to define and stay within the limits of this U-shaped curve to avoid complacency at one end and stress overload at the other. 

Staying within your stress “safety envelope” is critical for lots of other reasons since living on the edge in a chronic stress state has long-term health risks. It makes you more vulnerable to everything from the common cold to cancer. Among the most common and harmful effects of long-term stress are hypertension (with all its risks including heart attack, stroke, and kidney failure), insomnia, ulcer disease, infections (due to impairment of the immune system), increased risk of suicide, and alcohol and drug dependence. Stress-related health problems in our modern era are so common that they account for almost ninety percent of doctor visits. It has become such a drain on healthcare budgets that insurance companies now pay for professional relaxation and hypnosis treatment to counteract chronic stress syndromes. Some of these treatments are pretty similar to the tips I gave last month for managing acute stress in the cockpit. 

Chronic stress has significant impact on every system in the body. One of the least known and underappreciated effects is related to the immune system. The immune system protects us from a number of things from bacterial infections to metastatic cancer. To accomplish this, the immune system has several weapons in its arsenal. There are immune “killer” cells that are produced in response to exposure to viruses and bacteria (immunologists call them just that – killer cells). There are also immune hormones that are secreted directly into the blood and body tissues. This gives us a general immunity (called “natural immunity”) that provides an overall surveillance and protective function and a more specific immunity that is made up of antibodies to bad stuff that we have had previous exposure to or had prior immunization. Chronic stress suppresses both types of immune protection and therefore leaves us at a higher risk to all the things that the system is supposed to guard against. 

Another important function of the immune system is to provide constant surveillance for changes in any of the body’s cells that can be the start of tumors and cancer. Potentially dangerous structural changes actually occur frequently as cells replicate in the body. These abnormal cells are recognized and destroyed by those “killer cells” before the abnormal cells multiply further and grow into malignant tumors. Failure of this process obviously will lead to an early death from cancer.

The immune system also plays a major role in the early stages of wound healing by bringing specialized cells to the injury site that clean up wounds and begin the actual healing process. Repeated dumping of stress hormones (specifically cortisol) into the blood stream impedes the wound healing process and chronic exposure to stress leads to infection and delayed wound healing. Tissue biopsies of wounds from patients who are under high stress levels show that healing is 25% slower compared to patients who reported low levels of stress. 

Stress increases internal “rewards” associated with drugs and food, leading to changes in eating habits and weight gain as well as drug dependency. Overweight pilots are more susceptible to all kinds of health risks. Stress also contributes to various somatic disorders such as fibromyalgia, chronic fatigue syndrome, and depression. 

Stress affects both ends of the age spectrum. For young pilots wanting to start a family it has been shown that exposure to chronic stress for as little as 6 weeks has a negative impact on fertility. At the other end of the spectrum, stress accelerates the overall aging process and chronic diseases of aging such as depression and metabolic disorders.  High cortisol levels associated with ongoing stress lead to decreased bone density and, therefore, higher risks of fractures as people age. High cortisol levels associated with chronic stress are tied to a decline in memory that many older adults are already prone to experience and further worsens decision-making and cognitive acuity. I talked about several age-related changes in a previous article a few months ago – stress accelerates and multiplies all of those problems. None of these changes are good for older pilots in the cockpit.

In the last several articles we talked a lot about cognition, training, and decision-making, and it’s no surprise that chronic stress at any age has a major negative impact on these brain functions as well. Chronic stress affects the parts of the brain where all those skills we worked so hard to train and store are processed. A state of chronic stress can increase very short-term memories, kind of “flashbulb memories,” but it decreases long-term memory storage and consolidation of training lessons so there is really no actual learning.  Chronic stress shifts the kind of “learning” we accomplish from training to a habit-based algorithm so there is decreased reasoning and task flexibility, both of which can have dangerous outcomes in the stressed-out pilot.

There are a lot of things that can be done to control chronic stress and mitigate some of its negative impacts but the first thing that has to be done is to recognize this stressful condition exists. It isn’t possible to solve the problem and do anything positive about it until you acknowledge that it’s present. Tools and strategies that can alleviate chronic stress can be accomplished but it takes a lot of effort. 

Start by managing your time in such a way that you can get some of the heavy burdens of stress off your back. With a little bit more free time you can use relaxation exercises and start a physical exercise program. This is aimed at increasing your body’s production of “feel good” hormones like endorphins and dopamine. This also helps in treating mild forms of depression and anxiety that are so common with this condition. Just like in last month’s article where I talked about the value of controlled breathing to handle acute stress, in chronic stress states most people tend to breathe quickly with shallow anxious breaths. Deep, slow, full breaths have a profound effect on resetting the stress response. Try it, take a few deep breaths now and repeat this every couple of hours. This is also one of the foundations of ancient methods of meditation so get someone to teach you how to meditate. This will also help the mind and the body to relax and focus. 

Another big factor in stress is lack of quality sleep that is caused by increased stress hormones and leads to even more stress hormone release. Be sure to get a quality eight hours of sleep every night no matter what. Social support can also be very important, but this, again, requires taking the time to seek it out. Don’t be afraid to seek professional help if it comes to that and you can’t break the cycle of stress yourself.

Find that sweet spot between too little stimulation that leads to boredom and loss of mental focus and too much stress that will become overwhelming. Deal with stress straight on, realizing all the problems it can lead to if it goes unchecked. Think of yourself like you think about your airplane. You would never let parts of your plane grind on each other until the rivets pop. Don’t do that to yourself either.

Kenneth Stahl, MD, FACS

Kenneth Stahl, MD, FACS is an expert in principles of aviation safety and has adapted those lessons to healthcare and industry for maximizing patient safety and minimizing human error. He also writes and teaches pilot and patient safety principles and error avoidance. He is triple board-certified in cardiac surgery, trauma surgery/surgical critical care and general surgery. Dr. Stahl holds an active ATP certification and a 25-year member of the AOPA with thousands of hours as pilot in command in multiple airframes. He serves on the AOPA Board of Aviation Medical Advisors and is a published author with numerous peer reviewed journal and medical textbook contributions. Dr. Stahl practices surgery and is active in writing and industry consulting. He can be reached at [email protected].

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