Expert Commentary

Sleep disparities: An explainer and research roundup

A growing body of literature shows that many adults don’t get enough sleep, and that factors beyond an individual’s control can drive disparities and inequities in sleep, much like other areas of health.

An empty bed.
Photo by Cassidy Dickens on Unsplash

On average, humans spend about one-third of their lives sleeping, but the field of sleep medicine is young, dating back to only the 1970s, and research on sleep, particularly disparities in sleep, is still emerging.

Most sleep studies included only white men in the early years and other racial and ethnic groups and women and were not included in studies of sleep disorders until the 1990s, says Dr. Andrea Matsumura, a sleep medicine physician at The Oregon Clinic in Portland, Oregon, and a member of the Public Awareness and Advisory Committee at the American Academy of Sleep Medicine.

But the growing body of literature so far has revealed that sleep plays an important role in human health, and factors beyond an one’s control are linked to sleep problems, which can then affect overall health. Research also shows sleep deficiencies disproportionately impact those who experience other health disparities.

To take into account social, environmental and economic factors affecting sleep, researchers and experts use the term “sleep health” to create a holistic view of sleep.

“When I think about sleep health, I think about the right environment and the right amount of hours for sleep,” says Matsumura. “If the environment is too cold or too warm, or if you don’t have the right bedding, if you’re working three jobs to survive, or if don’t have money for a bed and you’re having to sleep in a chair, that’s going to affect your sleep health, because you’re not going to be able to get enough sleep.”

Sleep disparities

Lack of sleep is associated with chronic conditions such as type 2 diabetes, heart disease, obesity and depression. It can lead to car crashes and mistakes at work, leading to injury and disability. And it’s been associated with early death.

The association between lack of sleep and heart disease has been compelling enough that in 2022 the American Heart Association added sleep to its heart health checklist, along with nicotine exposure, physical activity, diet, weight, blood glucose, cholesterol and blood pressure.

About one-third of U.S. adults reported not getting enough sleep in 2020, according to data from the U.S. Behavioral Risk Factor Surveillance System, a nationally representative telephone survey that collects state-level data about health-related risk behaviors and is run by the Centers for Disease Control and Prevention. That makes for about 35% of adults who sleep less than 7 hours per day, a trend that has remained relatively unchanged since 2013. The CDC recommends 7 or more hours of sleep for adults 18 years and older.

The amount of sleep U.S. adults get varies based on age, sex, state and county of residence, and race and ethnicity.

More 25- to 44-year-olds reported not sleeping enough, compared with other adults, the CDC data shows. Sleep patterns change with age and most of the change happens between young and middle-aged adults and tends remain mostly unchanged in older adults, research shows.

When looking at men and women, slightly more men than women reported lack of sleep in 2020, the CDC data shows. These differences can be driven by menstrual cycles, pregnancy, menopause, and sleep disorders such as insomnia and sleep apnea. For instance, studies show that sleep apnea is more common in men than women, due to factors such as obesity, upper airway anatomy, hormones and aging.

Meanwhile, women tend to report more sleep problems, including inadequate sleep time and insomnia.

Matsumura, who has researched sleep inequities in women, says there’s a psychological component to higher rates of insomnia in women, as they’re more likely to be affected by domestic violence, workplace discrimination, misogyny in workplace and in the world.

“And that weighs heavy on women’s emotional well-being, which then infiltrates into sleep,” she says.

There’s also a delay in diagnosing sleep disorders in women, because oftentimes they’re “explained away,” by health providers, she says.

“‘Oh, you have kids. Oh, you’re taking care of parents. Oh, well, your husband’s away at work all the time.’ The classic, stereotypical reasons to explain away women’s symptoms, when in fact, they may actually have a sleep disorder,” Matsumura says. “And there haven’t been enough studies and data to really identify these disparities and really help close the gap.”

Sleep deficiencies also vary by race and ethnicity, the CDC data shows: 31% of white and Asian adults and 32% of Hispanic or Latinos reported that they were not getting enough sleep in 2020, lower than the national average of 35%. In comparison, 38% of American Indian or Alaska Natives, 43% of Black people, and 47% of Native Hawaiian and other Pacific Islanders reported sleeping less than 7 hours per night.

Drivers of sleep disparities

Although there’s been much emphasis on the importance of good sleep habits, sometimes called “sleep hygiene,” many other social and economic factors can override individual efforts.

Research in the past two decades has shown substantial inequities in sleep that parallel other racial, ethnic and socioeconomic disparities in health outcomes.

For instance, studies find that the stress of experiencing of discrimination can disrupt sleep.

A study published in Sleep Medicine in 2015 reviews 17 research papers and finds that discrimination — whether based on race, nationality, religion, gender, sexual orientation or other social factors — is associated with poorer sleep.  

The authors of a 2017 review paper published in Population Research and Policy Review, write, “The body’s ongoing anticipation of experiencing racism-related stressors disrupts sleep, a behavior highly responsive to stress reactivity.”

Another study, published in the Journal of Racial and Ethnic Health Disparities in February 2022, finds experiences of discrimination and psychological distress are associated with racial disparities in sleep. “Specifically, Black participants reported more experiences of discrimination, which was associated with greater psychological distress, which was related to poorer sleep health,” the authors write.

One study, published in the Journal of Racial and Ethnic Health Disparities in October 2021, focuses on the role of sleep and fatigue among first-generation Hispanic immigrants. It highlights the importance of understanding how racial discrimination can affect sleep, leading to health declines among Hispanic and Latinx immigrants.

Speaking during a virtual event on sleep hosted in February by the Harvard T.H. Chan School of Public Health, Dr. Carmela Alcántara, an associate professor at Columbia University who studies how discrimination and other stressors affect sleep and health, noted that it’s important to remember that the racial and ethnic disparities are not due to genetic differences, rather it’s the impact of social, economic and environmental factors that can affect sleep.

Buildings, roads, traffic patterns, noise, light pollution, neighborhood safety can disrupt sleep.

“We know for example that marginalized communities, racial/ethnic minorities, are more likely to live in neighborhoods with socioeconomic disadvantage and so that can include neighborhoods that might have higher policing and the influence of greater exposure to noise pollution, or greater exposure to light pollution,” said Alcántara during the Chan School webinar.

Shift work, which refers to a work schedule outside the conventional daytime hours can also affect sleep.

About 16% of the U.S. workers had non-daytime schedules in 2017-2018, including 6% who worked in the evening and 4% who worked at night, according to the Bureau of Labor Statistics.

Local, state and federal policies can also affect sleep.

“Social and health care policies affect financial stress, safety concerns, residential segregation practices, and individual autonomy, which may restrict or facilitate opportunities for achieving good sleep health,” write the authors of a 2020 paper published in Annual Review of Public Health.

Loneliness and social isolation are also associated with poorer sleep health.

Other factors include marital status and level of education. People who are married and have higher levels of education tend to report better sleep health.

“While some of these associations may not be causal, they point to the possibility of higher levels of stress due to everyday challenges encountered by more disadvantaged populations, owing to financial insecurity and less autonomy over their life choices,” write the authors of the Annual Review of Public Health paper.

Also important: Access, and lack of access, to health care.

“It’s access to the medicines for sleep, and access to [continuous] positive airway pressure (CPAP) machines, which cost a lot of money,” says Matsumura.

Below we’ve summarized three studies on the topic and listed a dozen more to help you with your reporting.

Research Roundup

Sleep Health: An Opportunity for Public Health to Address Health Equity
Lauren Hale, Wendy Troxel and Daniel J. Buysse. Annual Review of Public Health, January 2020.

The study: This review study highlights the state of the science on the role of sleep in public health and describes the findings that link poor sleep health in adults with heart disease, obesity, mental health and neurodegenerative diseases, such as Alzheimer’s disease and Parkinson’s disease. The authors define sleep health and factors associated with it. They also discuss the potential role of sleep in understanding health disparities. The authors also discuss recommendations and opportunities for interventions and the importance of promoting sleep health to achieve health equity.

The findings: The authors present two arguments. First, sleep health is a critically important — and underrecognized — factor in overall health and specific health conditions. Second, social and environmental factors affecting sleep health are often beyond the control of an individual. They consider improving sleep health a necessary step toward achieving health equity.

The authors recommend making studying sleep health disparities in vulnerable population a top research priority. Some of understudied populations include prison inmates, people living in homeless shelters, American Indian and Alaska native populations and patients in hospitals and nursing homes.

The authors write: “As with other public health epidemics, such as obesity, that have increasingly recognized the limitations of individual-level interventions alone, sleep health and public health researchers will benefit from adopting a multilevel approach for developing and disseminating evidence-based and scalable interventions. Sleep health promotion efforts should be considered at all levels of the socioecological model from the individual level up through the societal level. Employers, teachers, community members, health care providers, the media, and policy makers all have a role to play in changing and promoting a culture of sleep health.”

Sleep Disparity, Race/Ethnicity, and Socioeconomic Position
Michael A. Grandner, et al. Sleep Medicine, February 2015.

The study: This review of existing literature summarizes research on sleep patterns across racial and ethnic groups, discusses how race and ethnicity may be associated with sleep, discusses the role of socioeconomic standing with sleep patterns and offers future research directions.

The findings: Among the studies that researchers highlight is one that finds people who perceived racial discrimination when seeking health care were almost twice as likely to report more sleep difficulties, compared with those who didn’t have the experience of discrimination. They were also 60% more likely to report daytime tiredness and fatigue. “This sleep disturbance associated with racism not only explains part of the relationship between racism and depression but may also account for racial differences in sleep architecture,” the authors write.

The authors write: “Because race is a social category rather than an innate genetic trait, researchers must more carefully unpack the function race can serve in identifying the reasons for these sleep disparities. We recommend a research agenda that examines the role of race, racism, and socioeconomic disadvantage in sleep and the role of sleep in health disparities.”

How Did Trends in Sleep Duration in 2020 Compare to Previous Years and How Did They Vary by Sex, Race/Ethnicity, and Educational Attainment?
Connor Sheehan, Longfeng Li and Megan E. Petrov. Sleep Medicine, January 2023.

The study: The authors set out to explore how sleep duration changed during the latter months of 2020, considering that people’s sleep patterns were considerably changed during the first months of the COVID-19 pandemic. Using the CDC’s Behavioral Risk Factor Surveillance System data for American adults, they compared the 2020 data with 2013, 2014, 2016 and 2018. The total sample was 2,203,861. The BRFSS is a population-based phone survey of American adults 18 years and older in 50 states, Washington D.C., Guam and Puerto Rico.

The findings: Sleep duration significantly increased during the first months of the pandemic, particularly during the lockdown in March and April, potentially due to having more time because of working from home, or job loss. “For many Americans, the lockdown represented the first real respite from the quotidian stressors of work,” the authors write. However, it reverted to historical patterns by the fall of 2020, and the sleep disparities and trends based on sex, race, ethnicity and education stayed the same as before the pandemic.

The authors write: “More research is needed to understand the short and long-term consequences of the short-lived increases in sleep duration. Regardless of the potential consequences, these brief increases did little to abate social inequality in sleep. Overall, our findings illustrate how ingrained sleep disparities are even in the face of an exogenous shock to population-level sleep duration patterns.”

More studies to consider

Racial/ethnic Disparities in Subjective Sleep Duration, Sleep Quality, and Sleep Disturbances During Pregnancy: An ECHO Study
Maristella Lucchini, et al. Sleep, September 2022.

The Need for Social and Environmental Determinants of Health Research to Understand and Intervene on Racial/Ethnic Disparities in Obstructive Sleep Apnea
Dayna A Johnson, Chidinma Ohanele, Carmela Alcántara and Chandra L Jackson. Clinics in Chest Medicine, June 2022.

Acculturation Stress, Age at Immigration, and Employment Status as Predictors of Sleep Among Latinx Immigrants
Chanel Zhan, et al. Journal of Immigrant and Minority Health, March 2022.

Cultural Adaptations of Psychological Interventions for Prevalent Sleep Disorders and Sleep Disturbances: A Systematic Review of Randomized Controlled Trials in the United States
Carmela Alcántara, et al. Sleep Medicine Reviews, April 2021.

Rising Temperatures Erode Human Sleep Globally
Kelton Minor, et al. One Earth, May 2022.

Emergence of Racial/Ethnic and Socioeconomic Differences in Objectively Measured Sleep–Wake Patterns in Early Infancy: Results of the Rise & SHINE Study
Xinting Yu, et al. Sleep, March 2021.

A Workshop Report on the Causes and Consequences of Sleep Health Disparities
Chandra L. Jackson, et al. Sleep, August 2020.

Are Sleep Patterns Influenced by Race/Ethnicity — A Marker of Relative Advantage or Disadvantage? Evidence to Date
Dayna A. Johnson, et al. Nature and Science of Sleep, January 2019.

Discrimination, Sleep, and Stress Reactivity: Pathways to African American-White Cardiometabolic Risk Inequities
Bridget J. Goosby, Elizabeth Straley and Jacob E. Cheadle. Population Research and Policy Review, May 2017.

Why Sleep Matters — The Economic Costs of Insufficient Sleep
Marco Hafner, et al. Rand Corporation, November 2016.

Sleep and its Relationship to Racial and Ethnic Disparities in Cardiovascular Disease
John H. Kingsbury, Orfeu M. Buxton and Karen M. Emmons. Current Cardiovascular Risk Reports, October 2014.

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