The body’s nervous system is divided into two parts: the central nervous system and the peripheral nervous system. The central nervous system is also comprised of two parts: the brain and the spinal cord. The peripheral nervous system includes all of the other nerve cells throughout the body, including those connecting to organs and muscles.
The peripheral nervous system is divided into the somatic and the autonomic systems. The somatic system is the part of the nervous system responsible for the parts of the body that we think of as being under our control, like the arms and legs. The autonomic system controls parts of the body we tend to think of as functioning without conscious thought, such as heart rate and digestion.
The autonomic system is also divided into two parts: the sympathetic system and the parasympathetic system. A rough description of these two systems is that the sympathetic system is that which activates the body to respond to environmental stressors, while the parasympathetic system deactivates the body once the stressor has passed.
The sympathetic system is responsible for the “fight or flight (or freeze) response.” When faced with a danger, such as a car veering into our lane, our heart rate speeds up, respiration increases (or we hold our breath), blood moves away from the extremities to protect the internal organs (causing a decrease in temperature in hands and feet), and muscles become more tense, to name some of the changes in the body. After the danger passes, our body is supposed to calm back down as the parasympathetic response takes over: heart rate decreases, respiration decreases, hand temperature increases (due to the return of normal blood flow), and muscle tension decreases. This is the normal interaction between the sympathetic and parasympathetic systems. The problem is our stress / recovery system is not keeping up with the times.
The stress / recovery system has been evident in humans from our earliest days on the planet. The challenge for us living in our modern society is that our stress response has not evolved as our environment has. Our stress system is the same as the one that helped cave people defend themselves against saber tooth tigers. At that time, it was an effective system.
When we faced a tiger, there was typically one of three outcomes: 1) We fight the tiger and win, 2) We run away from the tiger, or 3) we get eaten by the tiger. Notice with each of these outcomes, the encounter would have been over relatively quickly. Because the tiger is more powerful and faster than a human, if the human fights, the fight must end quickly or he is not going to win. If he runs, again, he must get away quickly or he won’t get away. If the tiger wins, this outcome, too, will be fast. So our stress system worked well in these situations: quickly activate the body for fight / flight, maintain activation for a short period of time and then de-escalate the body once the threat has passed.
In our modern society, rarely are the stressors that we experience life threatening and rarely are they short-term. Sitting in traffic, dealing with a difficult boss, butting heads with family members: these are all examples of stressors that are usually not life threatening and not over within a few minutes. The stress response we have, however, remains the same as when we fought tigers: Our stress response system is not keeping up with the times. We get a call from our cranky boss and our heart rate increases, respiration increases, and peripheral skin temperature cools. The negative interaction with the boss could continue throughout the day and our body remains activated. As a result, rather than maintaining a healthy balance between sympathetic and parasympathetic responses, the sympathetic system gets overworked and the parasympathetic system becomes weaker.
The result of this imbalance has been well documented: increased stress leads to physiological problems like heart attacks and ulcers. Increased stress decreases mental clarity. During stress, we make more mistakes and we have difficulty remembering. Increased stress leads to interpersonal problems: the energy we need to be patient with our spouse or children has been exhausted by attempting to manage stress ineffectively and we end up yelling at our family members and kicking the dog. Later we wonder, “Who was that person?”
The parasympathetic response can be trained and can become stronger. As the parasympathetic response becomes as robust as the sympathetic response, we achieve stress / recovery balance. By the way, biofeedback, because of its focus on optimal performance, is an ideal intervention for restoring stress / recovery imbalance.