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Racial Disparities in Sleep: What the Science Says

/ September 4, 2020

The national spotlight is now shining on the many ways that Black Americans face inequality in society. But there is one important area where racial disparities exist that hasn't gotten much attention: sleep.

Racial disparities and sleep: what the research says

The Centers for Disease Control and Prevention (CDC) notes that more than a third of American adults don't get enough sleep on a regular basis. Research further shows that Black adults are almost twice as likely as white adults to experience inadequate sleep. That has serious consequences for overall health and wellness and can contribute to everything from high blood pressure to diabetes to heart disease.

Data from one study based on the annual National Health Interview Survey (NHIS), conducted by the CDC's National Center for Health Statistics, showed that Americans overall slept less during the years between 1977 and 2009. But the estimated number of Black Americans who get very short sleep (less than five hours) and short sleep (five to six hours) were consistently higher than their white counterparts.

Although the Black and white individuals who were assessed shared most of the same characteristics—including lower education level, lower income, smoking, drinking history, and physical inactivity—the researchers found that Black people who are short sleepers and very short sleepers “may be at greater risk" of experiencing deleterious physiologic and hormonal effects of insufficient sleep, which may predispose them to adverse heart and metabolic outcomes.

Why are Black Americans disproportionately affected by poor sleep?

It's important to point out there is no research suggesting a distinctive biological reason that Black people are so strongly affected by inadequate sleep and its repercussions.

That said, however, the factors that stand out as major contributors to the lack of sleep and its negative impacts on people of color can be linked to conditions that arise from systemic racism.

Using data from the 32,749 people over age 18 who participated in the NHIS, researchers found that some of the higher risk of short sleeping among Black people can be explained by living conditions, specifically those in inner cities. According to the study, living in a noisy, stress-inducing inner city is associated with an increased risk of short sleep.

What's more, a report from the Washington, D.C.-based Population Reference Bureau found that compared to white people, Black and Latinx people disproportionately work less traditional hours and are overrepresented among those who begin work during the evening, late night, and midnight/early morning hours.

Working during these times is associated with elevated risks concerning work hazards, family dissolution, health problems, and substance abuse—and is almost guaranteed to disrupt and inhibit a regular schedule of seven to eight hours of sleep. (Learn more about how shift work affects sleep.)

If inconvenient hours aren't disruptive enough, Black employees are more likely to report job strain, including less decision-making control in their work, more rapid and continuous physical activity, and less support from colleagues and managers. And stress on the job can lead to sleep deprivation.

How inadequate sleep affects Black Americans

Inadequate sleep, whether short or very short, means less time in slow-wave sleep, the deep sleep stage during which the brain and body are cleared and refreshed.

For a study reported in Health Psychology, researchers found that the 37 African-American participants had less slow-wave sleep and more physical fatigue than the study's 56 white participants. The researchers suggested that individuals who felt more connected to their ethnic group had a harder time getting adequate sleep because they felt the stress of discrimination.

That can contribute to and exacerbate a whole host of medical conditions. For example, the American Heart Association notes that African Americans are disproportionately affected by obesity, with 69% of non-Hispanic Black men and 82% of non-Hispanic Black women ages 20 and older considered to be overweight or obese.

Obesity increases the risk of high blood pressure (hypertension), which in turn increases the risk of heart disease and stroke. Type-2 diabetes also is closely associated with obesity and is a major risk factor for cardiovascular disease and stroke.

What does this have to do with sleep? The Sleep Foundation reports that sleep apnea, a breathing disorder that can be potentially dangerous and is also strongly linked to obesity, is more common and severe in Black people, particularly Black young adults.

Inadequate sleep affects all humans by altering multiple metabolic functions that lead to insulin resistance (Type-2 diabetes), possibly decreased energy expenditure, increased appetite, and immune system changes.

Researchers described in the Annals of the New York Academy of Medicine what they called “interacting epidemics" of sleep curtailment (not enough sleep), insulin resistance, and obesity—and the vicious cycle that occurs when individuals with obesity and/or diabetes experience psychological, endocrine, and anatomical abnormalities that in themselves interfere with sleep duration and quality.

What can be done to improve sleep—and health—in the Black community? It starts by addressing the inequities in education, employment, and living conditions that give rise to many of these health disparities.

As Eliseo J. Pérez-Stable, MD, director of the National Institute on Minority Health and Health Disparities, notes in a recently published blog post, real action to address systemic racism "will also improve the health of all Americans and move us toward a future in which all populations will have an equal opportunity to live long, healthy, and productive lives."

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