How Do You Know - Objectively - if Your Stress Level is Out of Control?
Most people are aware that “too much” stress is a significant risk factor in the progression of physical illnesses including cancer. What is far less clear is how to determine if your stress level is within acceptable limits or not. Whether the guided meditation, yoga, or deep breathing that you’ve committed to regularly doing is enough to offset the wear and tear of your everyday life? Recognizing how “stressed-out” you are is tricky if the mental state you’re is all too familiar. Though the problem of stress is commonly written about, the issue of its measurement is rarely addressed.
Heart-Rate Variability and Stress
One way to objectively begin to sort out how your body answers this question is to measure your Heart-Rate Variability (HRV). HRV is literally a measure of the beat-to-beat variation in time between heartbeats. For example, if your heart rate is 60 beats per minute, this doesn’t mean that your heart is beating once every second. Within that minute, there may be 0.8 seconds between two beats, .9 seconds between two others and 1.1 seconds between two more. So what does HRV say about stress level?
HRV can be thought of as a marker of our bodies’ biochemical response to acute stress and the method by which it returns to biochemical balance or allostasis. HRV takes the pulse of your nervous system. It’s a biomarker of the impact that making complex decisions, daily worries, the lingering impact of emotional trauma - has on your health and well-being
A high HRV means there’s a good amount of variation between your heartbeats. It typically means that the two components of your Autonomic Nervous System (ANS), the parasympathetic and the sympathetic nervous systems, can react to a demand in the environment (a stressful situation) and then recalibrate once the demand passes.
Low HRV means that there is little variability in the space between your heartbeats and this is suggestive that one branch of your ANS is more dominant (usually the sympathetic nervous system) and is sending stronger signals to your heart than the other branch. A chronic low HRV indicates your body is working too hard for some reason which leaves fewer resources available to dedicate towards other physiological activities.
HRV and Cancer
So what does HRV mean where cancer is concerned? Research published in mainstream journals can answer this question.
First: Cancer patients with a high HRV have been found to live longer compared to cancer patients with a low HRV (Zhou et al., 2016). A meta-analysis of 19 studies (based on humans not animals) found a high HRV to be associated with less progression of disease and better outcome across many cancer types (Kloter, 2018. Frontiers in Physiology).