How Does Alcohol Affect HRV?

Heart rate variability (HRV) is useful for monitoring an individual's quality of sleep, recovery, performance, and overall health. HRV is a measure of the variation in time between each beat of your heart. These variations between beats are measured in milliseconds and will increase and decrease throughout your day depending on your level and amount of activity or stress you may be experiencing. A higher HRV score means that there is more variability between beats and is a good indication of health and response to stress. A lower score however can signal when an individual is not as fit, sick, tired or stressed, and not recovered or recovering normally or at a healthy rate. 

Low vs. High HRV

HRV is typically higher when your heart is beating slower and the reverse occurs when your heartbeat quickens. Chronically low HRV can take a dangerous toll on the body, resulting in various health problems that drastically affect a person’s mental and physical health. Your autonomic nervous system (ANS) is a network of nerves that control your body’s unconscious processes, such as your breathing and heartbeat. ANS includes two branches, sympathetic (fight or flight) and parasympathetic (rest and digest), that help to regulate HRV. It is this careful balancing act between both sides of your ANS that helps to promote your body’s ongoing wellbeing and survival. If the body experiences too much of one or the other for an extended amount of time, it can be dangerous. Too much stress or activity or too much rest and inactivity. A healthy autonomic nervous system is one that is balanced between the two branches.

The purpose of this article is not to condemn or condone the use of alcohol but to simply explore its relation to your overall health, as well as what amount of alcohol may be hazardous for your health. It is no secret that alcohol affects all areas of the body, impacting many vital organs from the brain, heart, liver, and pancreas. In this discussion, we will be focusing mainly on alcohol’s effect on heart health and, more specifically, how it can affect heart rate variability (HRV). 

How Does Alcohol Affect HRV?

As previously discussed, a healthy balance in heart rate variability relies on the autonomic nervous system and its parasympathetic and sympathetic branches. When you are experiencing mentally or physically stressful situation such as a workout, the sympathetic branch activates the production of stress hormones, as well as an increase in your heart’s cardiac output and contraction rate while heart rate variability is decreased. And the reverse occurs once the stressful situation or activity has passed; the parasympathetic branch begins to restore homeostasis by increasing heart rate variability and slowing your heart rate. 

An area of the brain known as the amygdala inhibits parasympathetic pathways and excites the sympathetic pathways affecting the heart and its rate of variability. Under normal circumstances, structures in the brain suppress the amygdala which, in turn, maintains a healthy balance of the sympathetic system. However, studies have shown that the consumption of alcohol causes your resting heart to rise while also causing your HRV to drop. If the natural interplay between the two sides of your ANS are disrupted by one becoming more dominant, then those same high stress hormone levels will be present even at times when the body is resting. This can eventually cause major issues for the individual’s mental and physical health.  

The Lingering Effects of Alcohol

In addition to alcohol creating a drop in your heart rate variability, it has also been reported that the lingering effects of alcohol in the body may further suppress your HRV between a period of 4-5 days. Research has also shown that the liver, an organ responsible for cleansing the body of toxins as well as other important functions, may require up to an hour to rid a unit of alcohol from the body. If alcohol use progresses or worsens over time, the liver can become damaged which means that those toxins are not being adequately dispelled from the body, negatively affecting HRV even after alcohol consumption. Furthermore, the research has found that heavier drinkers have shown higher resting heart rate figures which is also linked to hazardous and potentially life threatening health conditions such as strokes and a higher risk of heart attacks. 

Alcohol’s Impact On Sleep And How It Relates To HRV

Just as heart rate and heart rate variability is unique to each individual, so are the effects of different types and amounts of alcohol consumed for each person. We can, however, state with certainty that the more an individual consumes, the greater their psychological and physiological consequences may be. Along with physical and psychological stress, poor sleep can also have a direct and damaging impact on your heart rate variability. Furthermore, many alcoholic drinks are followed by mixers that contain caffeine which also contributes to an increase in heart rate, as well as directly affects your ability to fall asleep and remain asleep.

Your body’s ability to achieve a restful night's sleep is vital to its efforts at restoring and repairing tissues, cells, and recharging for the day to follow and its necessary activities. Alcohol directly impacts sleep, lowering the quality and quantity. This in turn negatively affects HRV as your body is still in a state of stress even while asleep. Additionally, since alcohol is a diuretic, you may find your sleep is also disrupted throughout the night by more trips to the bathroom.

Role of Inflammation and Oxidative Stress

Much like the careful balance that must be kept in regards to the body’s autonomic nervous system and its two branches, the body also works to regulate and maintain the balance between free radicals and antioxidants. Free radicals are waste substances that are produced during normal metabolic processes by the body’s cells. To balance the amount of free radicals within the body, the cells also produce antioxidants which search out and neutralize the free radicals, helping to maintain a proper balance between the two. When the body does experience an imbalance between antioxidants and free radicals, oxidative stress can then occur which can harm cells in the body and disrupt normal body functions. 

Oxidative stress has been linked to many life threatening and health altering diseases including arthritis, stroke, respiratory and heart disease, immune deficiency, cancer, emphysema, Parkinson’s, and more. Additionally, oxidative stress is also particularly harmful to the blood vessels and the cells that line them, which can lead to the stiffening of arteries which results in coronary artery disease and high blood pressure. And while research does reflect a dramatic rise in risk of developing high blood pressure and heart disease in individuals who excessively drink, there is also research that supports low levels of drinking can still supply an increase to that risk, as well.