Stress and the nervous system


In this week’s column we investigate the impact of stress on the nervous system and on the way our DNA is selected.

The Autonomic Nervous System

The autonomic nervous system is the part of the nervous system that works automatically and independently of our consciousness. It controls our heart rate and breathing rate. It regulates the function of the visceral organs like the stomach, liver, kidneys, intestines, bladder, and reproductive organs. It does all the things that we don’t have to consciously do or control.

There are two divisions of the autonomic nervous system that the body can switch back and forth from. Both divisions evolved to regulate and protect the body and they both serve very important purposes. However, when the body remains in one division for too long, specifically the sympathetic division, problems occur.

Parasympathetic Division

The parasympathetic division is the wing of the autonomic nervous system that promotes healing and optimal function. It is also known as the “rest, digest, and repair” nervous system. When the body is primarily in the parasympathetic mode, the organs and tissues receive a rich supply of nutrients, perform their regular functions optimally, and regenerate. The parasympathetic is the mode your body is in when you feel most relaxed, at peace, and in deep sleep. The more time you spend in parasympathetic dominance the better the organs and tissues function.

Sympathetic Division

The sympathetic division is the wing of the autonomic nervous system that allows you to make it through a crisis. It is also known as the “fight or flight” nervous system. When the body is primarily in the sympathetic mode, blood flow and resources are shunted to the muscles and periphery of the body. Stress hormones like adrenaline and cortisol are produced, blood pressure increases, and blood sugar rises. The core visceral organs are almost abandoned in the sympathetic mode as things like digestion, bowel movements, urination, and most non-stress hormone-related hormone production significantly decreases. The body becomes focused on preparing the body to fight or run away from a threat.

The sympathetic division evolved to protect us from physical threats, and allows humans and other mammals to survive crisis situations. The sympathetic division is one of the most important mechanisms that has allowed humans to make it this far. However, we now live in a much different world than our ancestors did 1,000, 10,000 and 50,000 years ago. We don’t face the physical threats from predators and other events like our predecessors did.

Unfortunately, the body doesn’t know this, and still shifts into sympathetic dominance every time we perceive a threat. This threat could be very legitimate, like when you witness an accident, when you are threatened by someone, or when you are playing a competitive sport. However, most of the threats we face in our modern world are not life-threatening, but the body still shifts into sympathetic dominance. In fact, the vast majority of threats and stressors we face are mundane and not really that important - yet our body chemistry gets turned upside down when we perceive them to be threatening.

Think of what happens to your heart rate, blood pressure, breathing, posture, cognitive function, and bowels when you feel “stressed out”. Your physical and emotional bodies change drastically compared to when you are at peace. Now think about how much time you spend each day in sympathetic dominance. If there is no imminent threat, there is no need to be in sympathetic dominance. When you are waiting in line at the grocery store, stuck in traffic, arguing with your boss, applying for a new job, disagreeing with your spouse or disciplining your child, you don’t need to be in sympathetic dominance because these are not really the threats your body perceives them to be.

If there is no imminent threat, there is no need to be in sympathetic dominance.


There is a field of medicine and research called epigenetics that examines the way DNA is selected on a cellular level. Researchers in this field investigate the reasons why certain sequences are selected and others are not. While some questions can be answered by genetic or inherited reasons, it appears as though environmental factors play a large role. There is a great deal of research investigating the impact of stress on gene selection. Dr. Bruce Lipton is on the forefront of this research, and his book, “The Biology of Belief”, describes how stress alters the genes selected inside cells. In a nutshell, this research suggests that the way we think and handle stress impacts the selection of DNA and alters our physiology.

The way we think and handle stress impacts the genes selected on a cellular level and either leads to healthy cellular function or disease.


In next week’s column we will investigate the consequences of high cortisol levels due to stress.

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About the Author

Dr. Brent Barlow is a Naturopathic Physician practicing at The Kelowna Wellness Clinic in downtown Kelowna. Dr. Barlow has been in practice in Kelowna since graduating from the Boucher Institute of Naturopathic Medicine in Vancouver in 2009.

Naturopathic Doctors are trained as primary care physicians, and primarily use natural medicine to treat disease and promote wellness. Dr. Barlow believes strongly in identifying and treating the causes of disease rather than focusing on the treatment of symptoms.

Naturopathic medicine utilizes diet therapy, botanical medicine, nutritional supplementation, acupuncture, spinal manipulation and other physical medicine treatments to treat the causes of disease. Dr. Barlow also trained in the specialized treatments of prolotherapy, neural therapy, intravenous nutrient infusions, and chelation therapy.

Dr. Barlow is in general practice and welcomes all individuals and families. As a naturopathic physician he is trained to treat all health conditions in the manner that best suits the goals of each individual patient. He also has special interests in natural treatments for pain management and digestive health.

To learn more about Dr. Barlow's treatments or to schedule a consultation, visit his website at www.drbrentbarlownd.com or call 250-448-5610.

The views expressed are strictly those of the author and not necessarily those of Castanet. Castanet does not warrant the contents.

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