Sleep duration essential for heart health, new AHA recommendations say

The AHA publishes advisories that highlight the current state of knowledge on cardiovascular health and key areas for future research. Such advisories can help inform decision-making by clinicians and the formulation of healthcare guidelines. However, such advisories only serve to inform and are not guidelines.

An AHA advisory published in 2010 outlined the construct or concept of cardiovascular health (CVH) to help promote the maintenance of optimal heart health throughout a person’s lifetime. This construct emphasizes the prevention of CVD and the improvement of cardiovascular health.

The initial formulation of CVH included seven health factors and behaviors called Life’s Simple 7. These seven components included diet, physical activity levels, cigarette smoke exposure, body mass index (BMI), blood cholesterol, blood glucose, and cholesterol levels.

According to threshold values defined by the AHA, an individual’s levels of each of these seven components were categorized as being poor, intermediate, or ideal. An individual with ideal CVH would have ideal levels of all seven components.

Numerous studies conducted since 2010 have shown that individuals with ideal CVH had a lower risk of cardiovascular disease. Moreover, studies suggest that optimal cardiovascular health is associated with a longer lifespan and better overall health, including a lower risk of dementia, cancer, and kidney disease.

While these studies emphasize the validity of the CVH construct, scientists and clinicians have encountered some limitations while using the original formulation of CVH.

For instance, some of the criteria used for assessing CVH were either too broad or lacked sensitivity to evaluate changes in CVH over time. Moreover, the original CVH construct did not include sleep and social factors.

This has led the American Health Association to revise the construct of CVH. The new CVH construct includes sleep as the eighth component and is now called Life’s Essential 8.

An important contribution of this new construct is the inclusion of criteria for assessing CVH in children and pregnant people. The new construct also incorporates evidence from studies showing that brain health and CVH are closely intertwined.

Described below are the changes included in the updated CVH construct.

The original CVH construct described the quantification of the seven health behaviors or factors using the categories of poor, intermediate, or ideal. However, the use of these categories rather than a continuous scoring system makes the construct less sensitive to changes in the health of an individual over time or differences amongst individuals.

For instance, the original construct categorizes individuals engaging in moderate to vigorous physical activity for 1 to 149 minutes as having intermediate physical activity levels. However, the original CVH construct would have categorized both individuals who engage in a few minutes of physical activity and those who engage in 149 minutes as having intermediate physical activity levels.

To remedy this, the AHA has developed a continuous scale from 0 to 100 to better quantify the levels of each health factor or behavior. The average score of the eight health components is then used to measure overall cardiovascular health on a scale from 0 to 100.

Diet

The 2010 construct of cardiovascular health was focused on the quantities of intake of five nutrients, which included whole grains, fish, fresh fruits and vegetables, sodium levels, and sugar-sweetened beverages. However, sodium or sugar intake can be hard to track.

Instead, the updated CVH construct focuses on the intake of whole foods and healthy eating patterns.

Moreover, there are cultural differences in eating patterns and the new CVH construct notes that there are multiple different strategies for achieving healthy eating patterns.

The new construct emphasizes the benefits of DASH– and Mediterranean-style eating patterns, which have been shown to reduce the risk of CVD.

Blood glucose

The new CVH construct now includes measures of glycated hemoglobin (HbA1c) along with blood glucose levels, which were included in the original formulation. Hemoglobin is a protein that allows red blood cells to transport oxygen to different parts of the body.

Glucose can also bind to hemoglobin to form glycated hemoglobin (HbA1c), and HbA1c levels reflect blood glucose levels over the previous 2 to 3 months.

Elevated HbA1C levels are observed in individuals with diabetes and are associated with an increased risk of CVD.

Thenclusion of HbA1C along with blood glucose levels thus provides a more comprehensive measure of cardiovascular health.

Cholesterol levels

The original construct recommended the use of total cholesterol levels to assess CVH. Cholesterol in the blood includes high-density lipoproteins (HDL), low-density lipoproteins (LDL),very-low-density lipoproteins (VLDL), and triglycerides.

Higher HDL levels are associated with lower CVD risk, whereas non-HDL cholesterol, which includes LDL, VLDL, and lioprotein (a), is associated with an increased risk of CVD.

Life’s Essential 8 consists of non-HDL levels, instead of total cholesterol, as one of the 8 components to better reflect cardiovascular health.

Nicotine exposure, BMI, and blood pressure

The original construct only included cigarette use as an indicator of cardiovascular health. The nicotine exposure metric has now been expanded to include e-cigarettes, vaping, and exposure to second-hand smoke.

Life’s Essential 8 has retained the original definitions of ideal BMI and blood pressure described in Life’s Simple 7. The only change is that these metrics are now evaluated on a scale of 0 to 100.

The new addition: sleep

Studies have shown that inadequate or excessive sleep is associated with an increased risk of coronary heart disease. Although sleep duration is associated with the seven components included in the original construct, sleep quality can independently predict the risk of a cardiovascular event.

There is also some evidence to suggest that changing sleep duration can help modify the risk of cardiovascular disease.

The president of the AHA, Dr. Donald Lloyd-Jones, who led the advisory writing group, says:

“The new metric of sleep duration reflects the latest research findings: sleep impacts overall health, and people who have healthier sleep patterns manage health factors such as weight, blood pressure, or risk for Type 2 diabetes more effectively.”

“In addition, advances in ways to measure sleep, such as with wearable devices, now offer people the ability to reliably and routinely monitor their sleep habits at home,” he adds.

In addition to these eight factors, the new construct also highlights the role of psychological health and social factors in achieving cardiovascular health.

Stress and depression are associated with poor cardiovascular health most likely due to increased difficulty achieving a high cardiovascular health score, though depression itself may impact directly on cardiac health. In contrast, positive mental health is linked to better cardiovascular health.

Moreover, social factors such as socioeconomic position, racial discrimination, education levels, employment status, social isolation, and access to healthcare can also impact cardiovascular health.

“We considered social determinants of health carefully in our update and determined more research is needed on these components to establish their measurement and inclusion in the future,” Dr. Lloyd-Jones says.

“[S]ocial and structural determinants, as well as psychological health and well-being, are critical, foundational factors in an individual’s or a community’s opportunity to preserve and improve cardiovascular health.”
— Dr. Donald Lloyd-Jones

Dr. Sonia Anand, a professor of medicine at McMaster University, noted that the advisory was comprehensive but certain topics should receive more emphasis.

“Diet is always controversial and is very contextual; they do rely on U.S. data and metrics but this also limits the application to the U.S. population. They also mention the importance of considering social factors including ethnicity and race, along with diverse settings, and add a call for more research in this area. This is very important and to some, urgent,” she said.

“[The key gaps described by the advisory included information] on diverse populations/health equity, [and] this should be emphasized to ensure that funders of research and health promotion engage these communities in order to work within them to close these gaps,” she added.