Stress: Relation to performance, sleep, weight loss, and quality of life.

Thanks to a recommendation from my friend Patrick Ward, I picked up the book Why Zebras Don't get Ulcers by Robert Sapolsky. Needless to say, the book really opened up my eyes as to how the human stress response works and how it effects everything. The word stress as we know it is referring to allostatic load. We have all heard the term homeostasis in basic biology. The body will always tend to go back to normal. There are millions of reactions every second that mediate responses not only in the endocrine system, but also the cardiovascular system (heart, lungs, blood vessels), immune system (defense mechanism), cell metabolism etc. All of these systems are connected and play off of each other. A lot of times in science we like to compartmentalize things. There are different doctors for every system and organ that specialize. They know a lot about that system but sometimes may lose sight of how they all play together. I am by no means saying that we should restructure the whole medical field, but as we learn more about how the body works and moves, it is important to take into account a bigger picture. I believe this is where a better understanding comes from.

This post can be viewed as a very brief summary of the book. I took my favorite parts of the book to relate to my field which is human performance.

I am going to give a very brief explanation of what stress is but I encourage everybody to buy the book. First off a couple of key terms:

Homeostasis: The property of a system, either open or closed, that regulates its internal environment and tends to maintain a stable, constant condition.

Allostasis:  The process of achieving stability, or homeostasis, through physiological or behavioral change.


Those terms are very basic (Wikipedia did a fine job), but they really take meaning when we apply them to the most complex system known to us: the human body. They take even more meaning when we see how the two processes interact to keep us living. I will use a quote from Gray Cook, "The body will always sacrifice movement quality for movement quantity." He was talking about movement patterns, but this can be applied to a lot of things in the body. Here is an example from Sapolsky's book of the interplay between homeostasis and allostasis. "Suppose there is a water shortage in California. Homeostatic solution: mandate smaller toilet tanks. Allostatic solutions: smaller toilet tanks, water conservation, buy rice form Southeast Asia instead of doing water-intensive farming in a semi-arid state."

As you can see, allostasis takes a more global approach to a solution. Saplosky states that "Allostasis is about the brain coordinating body-wide changes, often including changes in behavior."

Now that we can acknowledge that the body is a complex system, made of smaller systems performing regulating tasks to keep us going. If the body did not have these systems, we would not be around long. Even drinking 2 cups of coffee would throw the body into a frenzy. Caffeine is a diuretic and it flushes water of of the system through urine. The brain senses this (through many pathways) and releases a hormone, that signals another hormone to tell the kidneys to re uptake water into the system because more water has left the body than usual in the past 2 hours since drinking the caffeine. You will not be thirsty right away but if you do not drink any water for a while, you will get very thirsty much quicker than if the caffeine had not been ingested. If the body did not regulate even this simple act that many of us partake in every day, we would die from dehydration from 2 cups of coffee. That would suck.

A stressor can be defined as anything that throws your body out of allostatic balance, and the stress response is your body's attempt to restore allostasis (Sapolsky). A very important concept emerges: regardless of the stressor-injured, starving, hot, cold, fight with spouse, boss wants to talk with you, upcoming test, cat is getting hair plugs, the body turns on the same stress response. Glucocorticoids (the stress hormones released by the adrenal gland) are released and mobilize glucose, fats, and proteins (varying degrees of each) go to the working muscles to run. In the Zebra running from the Lion's case, this is a good thing. You get to live (maybe). In the lion's case, catching food will save them from starving and coming back to their pack with nothing. See how the general stress response can respond in context? You would think the body would release a different chemical for every different psychological thought or experience right? Isn't the brain so complex that it should be able too? Well yes the brain is extremely complex but the beauty of the system comes in the regulation of these hormones and systems.In this case, the stress response is primitive and general, but how the body handles it is very complex.

The main point of the book is that we can release these glucocorticoids in reaction to a psychological stressor. Have you ever been up worrying about a test you have the next day? Ever been in a near accident at an intersection and your heart was beating for many minutes after the event? These are the same response. They are not bad. In fact, they are in part a primitive protective mechanism. Although we do not encounter many black bears or lions in our suburban cities, if we had to run, we would be able to because of this response.

So how can the stress response turn negative?

The stress response can turn negative if it never has a chance to turn off. Have you ever met somebody that complains of always being tired or always sounds "stressed out"? They always complain about lack of sleep and how negative everything seems to be. This person could be chronically stressed and even worse, be depressed. I am going to go over a couple of systems in the body to explain the connection of this stress response to our everyday life. Of course I am not a doctor and this should not be taken as medical advice, but my hope is to educate you about what happens. I also believe that we fear the unknown. I used to always think to myself: how can a change in a totally different system of the body affect another? Everything is connected. If we look at the body through these glasses,  the more knowledge we have about the "parts" will make our puzzle (the body as a system) easier to understand and make us able to draw some conclusions to. Maybe knowing a little more of how the body can respond to our everyday problems will help us deal with these stressors.

That was a basic overview of the stress response. I am going to divide the post up into parts because it might get a little long. I will be posting very soon about sleep. Stay tuned!

Sapolsky, Robert. Why Zebras Don't Get Ulcers. 3rd ed. New York: St. Martin's Griffin, 2009. Print.