Why start this blog by talking about Stress? There’s so much out in the media about stress, and so many seminars and workshops about stress. And “listicles” about the 7 things you can do to reduce stress!!!! (Why are they always odd numbers?) There’s a lot of information out there. But personally I find it all tends to swing between banal and overly technical. Stress is a part of life. Some people think it is good for us, motivating us to work hard. Is it really so terrible, and is it really that important manage it?
The short answer is yes.
But this blog is not about short answers, at least not that short!
Stress makes our lives less enjoyable, less meaningful, and one thing is clear- stress contributes to, and worsens, most chronic disease (for instance type II diabetes and cardiovascular disease, cancer), and can even increase inflammation. But the evidence base for how it does so is complex, especially for human studies. Part of the problem is that for scientists it is hard get a handle on just what IS stress. It reminds me of the story of the definition of pornography, supposedly given by a judge: “ I know it when I see it!”
We know when we are stressed, right?
When we think about stress, we usually think about our emotional reactions to, and perceptions of, challenging or obnoxious situations. These are subjective experiences, which are hard to quantify in the way that is necessary for scientific study. Subjective experiences of stress can be measured by numerical scales (“rate your stress over the last week 1-9”), but it can be hard to make a summary of your feelings over time. And there is no way that the rating can be independently verified. We can never know what someone else is feeling. But scientists like to find objective measures, things that can be quantified and compared across different people, such as biomarkers. Biomarkers are things such as hormones, which vary depending on the psychological or physiological state of an individual. Common biomarkers for stress are the hormones cortisol and epinephrine, which are released into the blood during stress. Which is great, but other things besides stress can cause these hormones to be released, so they are not necessarily reliable markers of stress. This has not stopped people from operationally defining stress as an increase in cortisol (or epinephrine).
Part of the problem is that there are different kinds of stress, which can have different effects on the body. The “classic” stress response involves activation of the sympathetic nervous system (epinephrine, aka adrenaline), and the hypothalamic-pituitary adrenal system that leads to cortisol secretion. The system is designed to respond to ACUTE stressors (like getting in a car accident, or almost getting in a car accident). Activation of the stress response in these situations is good. It saves our lives.
Part of the acute stress response is “piloerection”- fluffing our hair makes us look bigger and might scare away predators. This is probably more effective for cats! Other acute stress responses include a jump in heart rate, blood pressure and vasoconstriction, surge in blood glucose, pupil dilation, and heightened mental focus. (Sketch courtesy of Mara Gaykema)
In normal situations, when the acute stressor is over, the parasympathetic nervous system (e.g. the vagus, lots more on this later!) winds down stress responses and returns the body to a stable state. The problem is when we have stressors that are mild, but CHRONIC. Think mean boss, back-stabbing co-workers, partners with mid-life crises, teen angst. In these situations, stress responses do not get turned off, and the constant, low level of stress hormones leads to big problems with many systems in the body, including the immune, endocrine, and cardiovascular systems, and the brain. Chronic stress can even increase inflammation (more on that later), which is a hallmark of chronic disease.
But our conscious perceptions of stress are only half of the story. We can think of stress as following from the perception (or actuality) of threat. Problems with careers, interpersonal relationships, and frustrations are threats to the mind. Whenever we are sick or injured, the brain views this as a threat to the body, and responds as in many ways the same way it does to psychological stressors. So the sympathetic nervous system is activated, and levels of stress hormones such as cortisol are released. Inflammation consequent to illness or injury leads to the phenomenon of sickness behavior (more on that later)- depression, anxiety, fatigue, cognitive fuzziness, and sleep disruption. Appetite can be affected as well.
So we can be stressed, but not know it! Chronic illness is equivalent to chronic stress, and is associated with all of the problems experienced with chronic psychological stress. Unfortunately, most people with chronic diseases, and many of the practitioners working with them, are unaware that the illness is driving the fatigue, mood and cognitive problems. Chronically ill people can feel frustrated, like they should be able to “get it together”, but they can’t. This feeling, of course, is a psychological stressor. What you then end up with is a nasty vicious cycle: stress in the body (also known as “physiological” or “bottom-up” stress) induces stress in the mind (“psychological” or “top-down” stress), which enhances inflammation, making the stress in the body worse. Which makes the stress in the mind worse. And on and on. So it’s critical to somehow break that cycle, and that is going to be a major theme in future blog posts.