Sleep and Heart Health

Irving Smith, D.O.

Poor sleep is a curse of modern society.  We have become so habituated to getting what we want with the flip of a switch, the pushing of a button, or the popping of a pill, that we are out of sync with the normal rhythms of our natural environment and our bodies.

Many of us take sleep for granted, this essential one-third of our lives, often the first thing neglected when we are short on time.  A century ago, the average American slept nearly 9 hours per night.  It is now less than 7 hours per night.

In this article, we will explore some of the effects of sleep on heart health. Recent years have seen an enormous increase in the body of research associating poor sleep with stroke, heart disease, diabetes, and hypertension.

The leading cause of death in the United States over the past 100 years or more has been cardiovascular disease. Recently, the American Heart Association included for the first time routinely getting a good night of sleep as one of its 8 key components of cardiovascular health.

It is now well-established that there is a reciprocal relationship between sleep and heart disease; people with heart disease have a higher prevalence of poor sleep and patients with poor sleep are at greater risk for heart disease.

Sleep efficiency, defined as the ratio of total time spent sleeping to total time in bed, is a significant feature of poor health and pathological conditions, especially those involving the heart and brain.  Efficient sleep is sleep that is deeper and of a higher quality with fewer interruptions.

Chronic insomnia, defined as three or more nights per week of insufficient sleep lasting three months or more and not explained by another health problem, endangers the body, especially the heart and brain.

Cardiologists define major adverse cardiovascular events as cardiovascular death, congestive heart failure, heart attack, and stroke.  All of these are significantly higher in people with low sleep efficiency.

The odds of developing these debilitating conditions are considerably greater among those with a sleep-related breathing disorder, such as obstructive sleep apnea syndrome, the most frequently encountered disorder in sleep medicine. It is marked by intermittent airflow slowing or complete blockage during sleep. 

This interrupts essential heart and brain functions that only occur during sleep. These functions will not occur if the sleep is not on a more-or-less regular schedule for an adequate amount of time each night and with an open upper airway.

Cardiovascular disease is associated with changes in the nervous system, including the autonomic nervous system, which is responsible for many physiologic functions including heart contraction, heart rate, and resistance of blood vessels. 

The autonomic nervous system is composed of two components, the parasympathetic for rest and digest, and the sympathetic for fight and flight. Poor sleep can cause increased sympathetic activity which elevates blood pressure and inflammation. This, in turn, causes oxidative stress and damage to blood vessel walls.

The most accurate way of evaluating sleep is an overnight diagnostic polysomnogram, which is the gold standard for diagnosing and treating multiple sleep disorders.  Brain waves, oxygen levels, breathing rate, heart rate and rhythm, eye movements, and limb movements are all recorded and measured.

In select cases, out of center monitoring in the form of a home sleep apnea test can be used as a screening tool for relatively uncomplicated cases of suspected sleep-related breathing disorders.

It is important to address sleep health with your primary care provider.  This is especially true if you are tired and sleepy during the day, if your sleep is not restorative, or if you snore.

Sweet dreams!


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