I have been practicing medicine for over 23 years. While I have always known that stress can affect health, it has only been in the last few years that I have come to the realization that chronic stress is probably the main determinant of “dis-ease.”
Life as we know it is dependent on the maintenance of our bodily processes in a state of constant balance despite our ever-changing environment. In totality, these processes are known as homeostasis and any threat to this balance would be considered a stress or stressor. The body’s actions to maintain homeostasis in the presence of a stressor would cumulatively be known as the stress response.
Our nervous system coordinates the stress response. The autonomic component of this system is one of the most well known. It can be divided into two parts, the sympathetic (fight or flight) and the parasympathetic (rest, digest, and repair). The autonomic nervous system (ANS) controls the bodily functions we don’t have to think about like our heart beating, blood pressure regulation, digestion, and breathing.
The optimal state of affairs in the ANS is a balance more heavily weighted toward the parasympathetic. This is known as parasympathetic tone. While there is always some sympathetic activity, the “flight or fight” aspect really shouldn’t dominate until a threat is perceived.
While acute stress can promote beneficial adaptive responses – think lifting heavy weights as an exercise and the resultant increase in muscular strength – chronic stress is a state of sympathetic nervous system over activation, causing maladaptive responses in multiple body systems like: 1
· Sustained increases in blood pressure leading to damaged arteries, plaque formation, and the subsequent development of cardiovascular disease
· Chronic increases in blood sugar leading to diabetes and other metabolic derangements
· Immune system imbalance leading to sustained inflammation, susceptibility to infections, and autoimmunity.
These chronic stressors can take many forms:
· Biological: infections, toxins, food sensitivities, malnutrition
· Psychological/emotional: finances, relationships, work, chronic illness in a loved one
I truly believe that people underestimate the amount of stress that they are under and the effect that it is having on their wellbeing.
At the current time, there is no universally recognized standard for the evaluation of stress. There are psychological measures of stress using tests and questionnaires. You can also evaluate biological markers such as cortisol in saliva or blood or heart rate variability (HRV).
HRV, What it Means for You and Me
Although it’s hard to measure stress, the practice of increasing your heart rate variability is a measurable way to reduce stress. Here’s the scoop on HRV:
A healthy heart rhythm has healthy variability. For example, if your heart rate is 60 beats per minute, that doesn’t mean that it beats exactly one beat every second. There is variation among the intervals between each beat. The interval between two beats could be 0.99 seconds and 1.05 seconds between another two. This is HRV.
The heart has an intrinsic rate. This is the rate at which it would beat without any outside influence from the autonomic nervous system. Although this rate varies from person to person, it is typically around 100 beats per minute.
Normal parasympathetic tone lowers the heart rate from the intrinsic level, allowing more variability between successive heartbeats. Sympathetic activation elevates your heart rate from the intrinsic level allowing less room for variability.
Measuring the variability between heartbeats gives us an idea of the balance of the ANS. In an optimal state, when the parasympathetic is active and the sympathetic isn’t, the heart rate is lower and the HRV is higher. The stress response causes a reduced parasympathetic tone and/or increased sympathetic activation. This results in an increased heart rate and a lower HRV.
It has long been known that HRV amplitude is systematically related to breathing frequency, with higher HRV achieved with slower respiratory rates. These benefits occur with respiratory rates between 5 to 9 breaths per minute. In contrast, a normal respiratory rate is about 10-20 breaths per minute, so it will take some thoughtful practice to consciously (and temporarily) reduce your respiratory rate to achieve the desired HRV.
There are devices (watches, rings, ear clips, chest straps) and apps that measure HRV and guide your breathing to achieve a higher HRV. The type of biofeedback in these apps has been found to be beneficial in multiple disease processes like irritable bowel syndrome, hypertension, emphysema, asthma, anxiety, and depression. 2
Bringing it Home
With current technology, measurements of HRV are widely available. Compared to the measurement of laboratory values and psychological testing, HRV can be a more convenient and cost-effective option. Measurement of HRV also allows for biofeedback therapy based on breath work that engages the parasympathetic and decreases sympathetic activation, thus mitigating the negative responses of stress on the body. This is only one of many modalities for stress management.
Have you used any of these apps? Do you measure your HRV? How do you gauge the effect of stress on your health? What techniques have you felt have been the most helpful in managing your stress? Please share your thoughts below.
1. Schneiderman, Neil et al. “Stress and health: psychological, behavioral, and biological determinants” Annual review of clinical psychology vol. 1 (2005): 607-28.
2. Lehrer, Paul M and Richard Gevirtz. “Heart rate variability biofeedback: how and why does it work?” Frontiers in psychology vol. 5 756. 21 Jul. 2014, doi:10.3389/fpsyg.2014.00756