The nervous system is a complex network of nerves and cells that carry messages to and from the brain and spinal cord based on sensory input from our external and internal environments. Our understanding is growing about the interplay between these two settings and the effects they have on our health and vitality.

The voluntary nervous system is the part of the peripheral nervous system associated with skeletal muscle activity and voluntary control of movement, including facial expression, typing, writing, walking and moving in general.

The autonomic nervous system (ANS) is the part of the nervous system that controls functions that occur below our level of consciousness. These functions include sleep/wake cycles, level of arousal/alertness, heart rate, respiratory rate, endocrine function, immune function, digestive function and energy production and utilization.

The ANS is divided into two broad categories: sympathetic and parasympathetic.

  • The sympathetic component has to do with our relationship to the external environment. This is the hunter-gatherer orientation which corresponds to our level of alertness to the external environment in order to acquire things necessary for survival. It also relates to protection, self-preservation, and the fight or flight response.
  • The parasympathetic component has to do with our internal states. It is involved with restoration and repair, nourishment and detoxification, immunologic balance, and our innate sense of vitality and well-being.

Our level of awareness, ability to focus and intelligence reflect a complex interaction between the sympathetic and parasympathetic components of the ANS. Optimal health is associated with a dynamic, ever-adapting balance conditioned by the demands we face from moment to moment. When we are in good health, we experience flexibility and resilience in relation to the outer and inner environment and experiences.

Stress is a concept that has several different types of interpretations. Hans Selye, a noted physician and researcher, developed the concept that stress can be both positive (eustress) and negative (distress.)  Stress can be viewed as a physiological response to the demands put upon the body, but it can also mean the physical, societal or environmental factors impacting the individual (See Table I below.)  Moreover, stress can also be viewed as the individual’s own psychological perception of short- or long-term stress that challenges the individual’s coping abilities. Learning how to perceive stress differently can help divert the negative stress response. It is not essential to eliminate stress but to ensure sufficient recovery.

Sympathetic dominance occurs when the sympathetic nervous system activity predominates over parasympathetic activity. It is the normal state for most people in the modern world. We are constantly pulled to focus our attention on the outside environment where we attend to our families, our jobs and the concerns of our community. We lose our flexibility and resilience and cannot find our way back to a restorative, reparative inner world that is so necessary for optimal health and well-being.

Chronic stress is associated with sympathetic dominance and ANS dysfunction. This can occur as a result of stressful situations in our families, our workplaces and our communities. This is a common syndrome in people who are predisposed to illness or who have chronic illnesses. When we lose the skills to maintain the balance between sympathetic and parasympathetic states, we develop a rigidity that leads to chronic disease.

Anxiety and depression are obvious consequences of this phenomenon. Other health problems include:

  • Cardiovascular diseases such as hypertension and hardening of the arteries (atherosclerosis).
  • Endocrine/metabolic problems such as metabolic syndrome and diabetes
  • Immunologic problems such as autoimmune disease and arthritis
  • Neurological diseases such as memory disturbance and chronic pain syndromes
  • Neoplastic diseases/cancer has a strong relationship to autonomic nervous system imbalance
  • Sleep disorder

Sympathetic dominance is associated with decreased quality of life and decreased survival in people with diabetes, heart disease, neurological disease and cancer. It is associated with an increased chance for reoccurrence in people who have been treated for cancer.

The loss of parasympathetic function is associated with age-related sleep disorders. The restoration of parasympathetic function will improve sleep quantity and quality. It produces the environment that allows for detoxification, restoration and repair that occur when we are experiencing a healthy sleep pattern.

Table I:  Different Stress Factors

The following is an abstract from a medical journal that speaks to the importance of autonomic nervous dysfunction in chronic disease:


Conditions of aging as manifestations of sympathetic bias unmasked by loss of parasympathetic function

We propose a unifying hypothesis that many clinical consequences of aging are pleiotropic manifestations of the loss of parasympathetic function that occurs during post-reproductive senescence. The loss of parasympathetic function unmasks the baseline sympathetic bias inherent in the end-organs, resulting in the familiar signs of aging including tachycardia, constipation, insomnia, erectile dysfunction, fluid retention, and systemic inflammation. These consequences in turn may contribute to many of the common diseases associated with aging including type-2 diabetes, Alzheimer’s, atherosclerosis, and cancer. Maintenance and restoration of parasympathetic function may enable upstream control over the deleterious aspects of inherent end-organ adrenergic bias.

Medical Hypotheses

Volume 62, Issue 6, June 2004, Pages 868–870

One strategy for quantifying sympathetic dominance is through heart rate variability (HRV). HRV means the variation in time between consecutive heartbeats. HRV increases during relaxing and/or recovering activities and decreases during stress. Typically, there is an inverse relationship. There is more variability when the heartbeat is beating slow compared to fast. People with sympathetic dominance have reduced HRV, which is associated with an increased incidence of chronic disease.

We use two different technologies to measure HRV in our office. The first is a six-minute finger screen, but this is not a definitive measure. The second is a 72-hour test by FirstBeat Technology that is a more conclusive measure of HRV and our ability to manage stress. The data is acquired from a small, innocuous device, with electrodes that are applied to your body for three days. The information gathered is uploaded to a computer software program for an individualized analysis. It provides valuable information about the events of the day and time of the day when stressful events are having the most significant impact. More importantly, it tells us whether the individual is developing an adequate parasympathetic tone at night, a critical time when repair and restoration occurs. The results are interpreted by a wellness professional and a plan of action is created for improvements in stress management, exercise, and/or quality of sleep.

Sympathetic dominance can be improved by applying the principles of integrative medicine. This includes diet and nutrition, activity and exercise, herbal therapies and self-regulation therapies such as mindfulness, open-focus and EEG biofeedback. Committing to a healthier lifestyle can shift how we experience and respond to stress.

Our practitioners support patients in creating individualized programs with regular feedback to help them reach their health goals. To find out more about FirstBeat HRV and to set up an evaluation, please contact our wellness professional Sara Cooper, MS, LDN, CNS, CSCS at: