Posts Tagged ‘Parasympathetic nervous system’

The Importance of the Vagus Nerve in Relieving Stress

September 7, 2013

The vagus nerve is the 10th cranial nerve. It connects our brains to our lungs, digestive tracts, heart, and the parasympathetic nervous system. Remember that our sympathetic nervous system alerts us to new things and danger. The parasympathetic nervous system is responsible for helping us relax and calm down. The stronger the activity of our vagus nerve, the more readily we can assume a feed and enjoy state rather than being stressed out. The strength of this vagal activity is known as vagal tone.

The vagus nerve’s interplay with the heart rate as we breathe can be used to infer vagal tone. Inhaling temporarily suppresses vagal nerve activity. This increases heart rate that helps oxygenated blood circulate. When we breathe out, our heart rate slows. The larger the difference between our heart rate when breathing in compared with breathing out, the higher our vagal tone.

An article in the New Scientist1 explains why we should care about vagal tone, and what we can do to improve it. There are physical health benefits. The vagus nerve plays a role in stimulating insulin production. Consequently, people with low tone are not as good as those with high tone at regulating their blood glucose levels. They also have difficulty suppressing inflammation. These factors are association with heart failure, stroke, and diabetes, so it is not surprising that thee is a strong link between low vagal tone and dying from cardiovascular disease. There are also mental benefits. People with higher vagal tone tend to be intellectually sparkier. They are better able to focus their attention and have better working memories.

Naturally, the question is how can vagal tone be improved. Loving kindness meditation was highlighted in the New Scientist article. Buddhist monks will spend hours in this type of meditation. Given the state of the world, one might conclude that their efforts are ineffective. However, regardless of the state of the world, these monks should be in superb physical and mental health. Fortunately, it does not appear that lengthy meditations are needed . Here is the protocol described in the article:

Find a position that makes you feel relaxed, yet alert. With your eyes closed, try to envisage your heartbeat, and then consciously concentrate on your breathing. Now visualize someone—it can be yourself, a loved one, or someone you barely know—and think of their good qualities. Once you are feeling positive towards them, repeat these traditional phrases of loving kindness meditation: May X feel safe: May X feel happy: May X feel healthy: May X live at ease. After a few minutes, let go of X’s image and start thinking nice thoughts about someone else.

The article mentions people mentally wishing happy thoughts to strangers they are passing. Research into this area is fairly new. It does not seem that loving kindness meditation, although certainly worthwhile, is necessary to increase vagal tone. However, it is quite likely that positive thoughts and some type of meditation are important. Some unpublished research has shown that just reflecting on positive social experiences during the day boosts vagal tone. Physical exercise is also likely to be beneficial

1Young, E. (2013.Wishful Thinking, July, 46-49.

© Douglas Griffith and healthymemory.wordpress.com, 2013. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and healthymemory.wordpress.com with appropriate and specific direction to the original content.

Is Our Evolutionary Heritage Placing Us at Risk?

July 21, 2013

I believe it is common knowledge that one of the reasons those of us living in the developed countries tend to be overweight, or obese, is that in the earliest stages of the development of our species it was beneficial to survival to store up bodily fat when food was available. This enabled our species to survive when food was not readily available. It was also beneficial to consume foods high in calories. As food is readily available in developed countries today, and there is a tendency to favor foods high in calories. So behaviors that once were beneficial, are now no longer beneficial, and are even potentially harmful.

There is an analogous situation with respect to how we respond to stimuli and how we process information. In earlier times, there were many sources of danger both from other species and within our own species. Consequently, it was beneficial to respond quickly to potential dangers. It is our sympathetic nervous system that responds to potential danger and produces stress. Our parasympathetic nervous system has the role of counteracting our sympathetic system to reduce stress and calm ourselves. An argument can be made that our evolutionary heritage has left many of us with a predisposition in favor of the sympathetic nervous system even though, for most people and in most places, this predisposition is no longer beneficial. There are other factors in addition to a likely evolutionary predisposition that increase the problem. Given the preponderance of crime shows and violence on television and in the movies, people develop a sense of danger that is not proportionate to their actual individual risk. News reports of violent crimes, mass shootings, and terrorist acts increase the sense of danger, when the actual probability of their occurring to most individuals is extremely low. Few people are aware that about 50% of law enforcement officers retire without ever having fired their weapons in the course of their duties. Even with the vast news coverage that has been given to the Trayvon Martin case, there has been virtually no mention of the fact that if there had been no gun, no one would have been killed, and there would have been no trial. The belief that the solution to the problem of gun violence is the arming of more people is clearly false. More guns increase, not decrease, the likelihood of violence.

As has been mentioned in previous healthymemory blog posts, System 1 processes (if you don’t know what System 1 processes are, enter System 1 into the blog search box) were especially beneficial to the early survival of our species. And while System 1 processes are beneficial most of the time, they can have erroneous outputs and System 2 processes must be engaged. A very simple way of thinking about this is that System 1 is reacting, whereas System 2 is thinking. Mindfulness involves shutting down System 1 processes and allowing the flow of System 2 processing.

More information can increase the resort to System 1 processing in an effort to try to keep up with the information overload. Nate Silver notes in his book, The Signal and the Noise, a surprising result of an earlier technological innovation that greatly increased the dissemination of information, the printing press. It produced the Protestant Reformation that plunged Europe into war. “From 1524 to 1648, there was the German’s Peasant War, the Schmalkaldic War, the Eighty Years War, the Thirty Years War, the French Wars of Religion, the Irish Confederate Wars, the Scottish Civil War, and the English Civil War…The Thirty Years War alone killed one-third of Germany’s population, and the seventeenth century was possibly the bloodiest ever, with the early twentieth staking the main rival claim.”1

One can argue that the advent of the internet has increased the dissemination of information, produced information overload, and has resulted in similar problems: terrorism, religious wars (in the 21st century if you can believe it), and political polarization, which has impeded, if not prevented, effective government.

The solution to this problem is clear, it is mindfulness. We need to try to establish contact with reality, with our bodies, and our minds. (Enter “Mindfulness” into the healthymemory blog search block to learn more about mindfulness).

1Silver, N. (2012). The Signal and the Noise. New York: The Penguin Press., p. 4.

© Douglas Griffith and healthymemory.wordpress.com, 2013. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and healthymemory.wordpress.com with appropriate and specific direction to the original content.

Optimism

October 19, 2011

There are many benefits that accrue to those who are optimistic.1 Optimists recover better from medical procedures, and have healthier immune systems. They live longer both in general and when suffering from conditions such as cancer, heart disease and kidney failure.2

It is common knowledge that negative thoughts and anxiety can make us ill. The belief that we are at risk triggers physiological pathways such as the “flight or fight” response by the sympathetic nervous system. Although these have evolved to protect us from danger, when they are switched on long-term they increase the risk of conditions such as diabetes and dementia.

The new perspective on optimism is that positive beliefs don’t just work by quelling stress. They have unique positive effects. Feeling safe and secure and believing things will turn out fine seems to help the body maintain and repair itself. A review of recent studies concluded that the health benefits of positive thinking happen independently of the harm caused by negative states such as pessimism or stress, and are roughly comparable in magnitude.3

It is thought that optimism reduces stress-induced inflammation and levels of stress hormones such as cortisol. It might also reduce susceptibility to disease by dampening sympathetic nervous system activity and stimulating the parasympathetic nervous system. The parasympathetic nervous system governs the “rest and digest” response—the counterpart to the “fight or flight” response.

Even if you are not an optimist, you can train yourself to think more positively, and it seems that the more stressed or pessimistic you are to begin with, the better it works. David Cresswell of the Carnegie Mellon University asked students facing exams to write short essays on times when they had displayed qualities that were important to them. The aim was to boost their sense of self-worth. Compared to the control group, these self-affirmed students had lower levels of adrenaline and other fight or flight hormones in their urine on exam day. The effect was greatest for those students who had been most worried about their exam results.4

Tali Sharot has written an interesting book claiming that we have an optimism bias because it provided us with an evolutionary advantage.5 When most people are asked what is going to transpire in the upcoming month, they tend to give an overly optimistic account. Similarly, when asked to provide an estimate of their longevity or of their having certain diseases, they also tend to provide overly optimistic accounts. The people who are able to provide fairly accurate estimates for these same questions tend to be those who are clinically diagnosed as being mildly depressed. This phenomenon is called depressive realism.6 So the idea is that truly accurate realism can be depressive. A species of mildly depressed individuals probably could not have evolved.

To conclude, although optimism can be good, there is also the possibility of too much of a good thing. See the Healthymemory Blog Post, “Can Optimism Be Bad?”

1Much of this post is based on an article, Think Positive, by Jo Marchant in the New Scientist, 27 August 2011, p. 34.

2Annals of Behavioral Medicine, 39, p.34.

3Psychosomatic Medicine, 70, p.741.

4Health Psychology, 28, p.554.

5Sharot, T. (2011). The Optimistm Bias: A Tour of the Irrationally Positive Brain., New York: Pantheon Books.

6Alloy, L.B., & Abramson.  (1979) Judgment of contingency in depressed and nondepressed students:   Sader but wiser.?  Journal of Experimental Psychology:  General, 108, 441-485.

 

 

© Douglas Griffith and healthymemory.wordpress.com, 2011. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and healthymemory.wordpress.com with appropriate and specific direction to the original content.