A version of this story appeared in Science, Vol 374, Issue 6567.
On a Sunday morning earlier this month, Girardin Jean-Louis attended the regular mass service at Trinity Baptist Church in North Miami, Florida. He wasn’t just there to worship, though. After the hourlong service, he stepped to the lectern, microphone in hand, and spoke to the congregation—most of them Black—about the importance of good sleep. “I was using the Bible, talking about how important sleep used to be for all of the kings and queens,” he says. “They always had a sage [who] would interpret the dreams, so I use this to show dreaming is very important.”
A sleep researcher at the University of Miami, Jean-Louis splits his time between the lab, where he studies the disproportionate toll of sleep deficiency on communities of color, and places at the center of many Black communities: churches, barbershops, beauty salons. There, with the help of pastors, barbers, and other influential figures, he preaches the importance of sleep. Being a Baptist helps, too, he says. “I know the language, I know the lingo.”
He is trying to address a historically neglected aspect of racial inequity. Far more Black and Hispanic people than white people report routinely getting less than 6 hours of sleep, well short of the recommended 7 to 9 hours for adults. Studies have shown nonwhite people take longer to fall asleep, wake up more during the night, and spend less time in deep sleep—a stage of sleep important for strengthening the immune system, forming memories, and restoring the health of cells. Sleep disorders, such as obstructive sleep apnea, are up to twice as common in people of color. All of this increases the risk of chronic diseases aggravated by poor sleep. “Sleep is a privilege,” says Dayna Johnson, a sleep epidemiologist at Emory University. “If we can target sleep, we might be able to reduce the burden of all types of diseases among racial minorities.”
Researchers like Johnson and Jean-Louis are trying to understand what causes these disparities and how scientists, physicians, and policymakers might implement solutions—and begin to right what they see as an underappreciated source of social and health injustice. “Sleep deficiency is literally undermining the fabric of society, particularly in minority and low socioeconomic populations, because they bear the disproportionate burden of the associated risk,” says neurobiologist Marishka Brown, director of the National Center on Sleep Disorder Research at the National Heart, Lung, and Blood Institute. “Sleep is a modifiable source of inequity.”
Jean-Louis first became interested in sleep disparities when he was a postdoctoral researcher in psychiatry at the University of California, San Diego, in the late 1990s. In a survey study, he and colleagues found nonwhite men in San Diego slept about 1 hour less per night on average than white men. Jean-Louis recalls wondering why at the time: “Is it a function of health care access? Is it a function of lifestyle factors?”
Some evidence points to biological factors—such as differences in upper airway anatomy that might make people of Asian descent more prone to sleep apnea, in which soft throat tissue obstructs the airway and causes waking. But most researchers think socioeconomic and environmental factors are the main cause of these disparities. “I want to move attention away from those genetic explanations because what that means is that it’s that person’s individual responsibility to fix that issue, versus shining a light on the structural and social factors,” says Carmela Alcántara, a clinical psychologist at Columbia University.
In recent decades, researchers have identified some of those social and environmental factors. For example, more Black and Hispanic people work nontraditional hours, including night shifts, which makes it difficult for them to get a good night’s sleep. A 2010 study of 340 workers at an extended-care facility in Massachusetts, for example, found Black and Hispanic employees were twice as likely as white ones to work the night shift and slept up to 1 hour less per day on average than white people in general.
Although shift work affects sleep in all ethnic groups, Hispanic people, especially those who are unemployed, may experience a more specific sleep disrupter. Alcántara’s research has found acculturation stress—distress that results from adapting and integrating into a new culture—increases the severity of insomnia symptoms. “There’s something unique for this population about this specific sociocultural stressor.” In addition, discrimination related to their ethnicity and status as immigrants also affects sleep in Hispanic people, she says.
Indeed, more than a dozen studies have identified racial discrimination as a contributor to sleep disparities. In one published last year, Johnson and colleagues asked 1458 people in Detroit who met clinical criteria for insomnia how often they have been treated badly or unfairly because of their race or ethnicity. Black people reported more discrimination and more severe insomnia symptoms than white people, and a statistical analysis determined discrimination accounted for 60% of their insomnia severity.
Environmental factors also cut into sleep. A 2020 study that combined data from the U.S. census with an atlas of light pollution derived from satellite data found Black, Hispanic, and other people of color tend to reside in brighter areas, where they are exposed to approximately twice as much ambient light at night as white people. Exposure to artificial light from the street and commercial buildings has been found to suppress melatonin—a hormone that helps initiate sleep. That causes people to fall asleep later at night, resulting in poorer sleep overall.
Black, Hispanic, and Asian people in the United States are also exposed to disproportionately high levels of particulate air pollution. Exposure to this type of pollution can cause inflammation of the nose and throat, and some evidence suggests chronic exposure can worsen sleep apnea and increase daytime sleepiness. And then there is nighttime noise, which a 2017 study at hundreds of sites across the United States found is higher in neighborhoods with a higher proportion of Black residents.
“Our ZIP code is as—if not more—important than our genetic code,” Johnson says.
“Sleep is the most primordial human activity,” says Azizi Seixas, a precision medicine researcher at New York University’s (NYU’s) Langone Health. “We can’t do without it.” Besides leading to drowsiness and impaired cognition, lack of sleep also takes a toll on the body.
As early as the 1980s, studies linked sleep apnea and shift work with hypertension and coronary heart disease. When we sleep, our blood pressure goes down, Johnson explains. “We give our blood vessels a break, essentially,” she says. But if sleep is interrupted or shortened, the body maintains a higher blood pressure at night—what physicians call nocturnal hypertension—which raises the risk of heart disease and stroke. Many studies have shown Black shift workers have higher chances of developing hypertension, compared with white shift workers.
Recent studies have firmed up the link between poor sleep and cardiovascular disease in people of color. A 2017 paper published in the Proceedings of the National Academy of Sciences showed that among 426 people in three U.S. cities, Black people had a 12.5% higher cardiometabolic risk—the chances of having a cardiovascular event, such as a heart attack or stroke, or developing diabetes—than white people. They also slept 40 fewer minutes per night than white people and spent 10% less time asleep while in bed, a measure of sleep efficiency. The researchers estimated that together, those factors accounted for more than half of the racial difference in cardiometabolic risk.
Poor sleep may also contribute to worse outcomes in Black people with heart problems, a 2018 study found. Black patients who slept fewer than 7 hours at night in the month after a heart attack or episode of unstable angina were at greater risk of another event—or dying—compared with Black people who slept more. Reduced sleep did not have the same detrimental effect for white people with a similar cardiac health history.
The health impacts aren’t limited to cardiovascular disease. When we don’t sleep enough or our sleep-wake cycle is disrupted, hormone imbalances prompt hunger, which can cause overeating and could contribute to obesity, Johnson says. Researchers have also found that disturbed and insufficient sleep causes alterations in glucose metabolism that can contribute to insulin resistance, a precursor to type 2 diabetes. Obesity and diabetes already disproportionally affect people of color, and researchers suspect sleep disturbances could be making those conditions worse.
Sleep apnea could be having dire health consequences among Hispanic and Black people, says physician-scientist Alberto Ramos at the University of Miami. Large epidemiological studies have suggested apnea and related breathing problems are twice as likely in Hispanic people compared with white people—and often go undiagnosed. In an observational study with 14,440 Hispanic people, Ramos and colleagues found less than 1% of those with apnea had a proper diagnosis.
Poor sleep and sleep apnea have been linked to neurodegenerative diseases—especially Alzheimer’s disease—in the general population, Ramos notes. And, he adds, “We know that Hispanics have a two to four times higher risk for dementia.” Sleep apnea is one possible contributor to elevated dementia rates and cardiovascular disease—racism and neighborhood noise and air pollution are others—that Jean-Louis and Ramos plan to investigate in the varied Black and Hispanic communities in Miami. At the recent event at Trinity Baptist Church, Jean-Louis recruited 10 new participants.
After Jean-Louis moved from San Diego to New York City in 2000 to work at the State University of New York Downstate Medical Center in the heart of Brooklyn, he started to look for ways to engage with the many communities of color near his lab. But he learned the hard way that being Black himself did not mean automatic rapport. When Jean-Louis, a native of Haiti, showed up at a neighborhood barbershop with a clipboard and started to ask people about their sleep habits, they didn’t take him seriously. He soon learned to first build trust with the barbershop owners, who would then convince their clients to open up.
Once they did, Jean-Louis found many misconceptions. For instance, he learned many people in these communities do not think of sleep apnea as a problem. “In their minds snoring is a good thing—it means you’re in deep sleep,” he says. But in fact, snoring is a sign that you’re not breathing well during slumber.
Later, when he moved to NYU, he sought other trusted intermediaries. He and Seixas teamed up to recruit volunteers, nominated by their own communities, to be “certified sleep educators.” After an 8-week training program on sleep health and counseling, the educators provided tailored advice and emotional support to people in their community, and convinced many to get screened and treated for sleep apnea. During the pandemic, the educators helped convey accurate scientific information about COVID-19—an unintended benefit that demonstrates how trusted they’ve become, Jean-Louis says. “It was a great surprise,” he says. “They were wonderful.”
Such educators can deliver tailored and culturally relevant information. “A lot of the guidelines and solutions do not take into account the lived experience of marginalized communities,” Alcántara says. The mostly white experts who recommend a certain amount of sleep, Seixas says, “blindly accept and assume that people can get that sleep.” Recommendations have to be applicable to everyone, even a single mom who works two jobs and has two kids, he says.
For a study published last year, Jean-Louis and his team created a website that features Black people sharing their experiences with sleep apnea. “They can see themselves through those stories,” Jean-Louis says. “If your brochures only depict white men and women … [Black people] don’t relate to this, they don’t even open it up.” In a randomized trial, the researchers found that participants who used the website reported feeling more able to seek sleep apnea evaluation and adhere to treatment, which involves a machine that delivers pressurized air through a face mask to keep the airway open.
Jean-Louis says Black patients sometimes don’t feel welcome in sleep clinics and mistrust medicine and physicians, so he advocates testing these patients at home. Seixas is developing a kit with several wearable devices to screen patients of color for sleep disorders, upload their data, and then provide tailored sleep health advice.
Alcántara, meanwhile, is working to improve access to insomnia therapy for Hispanic people. Therapy for Spanish speakers “is virtually nonexistent,” she says. In a review published earlier this year, Alcántara and her colleagues found that of 8182 randomized clinical trials of behavioral interventions to improve sleep, only 7% targeted underserved groups, and only one included Spanish in the treatment.
Cognitive behavioral therapy for insomnia (CBT-I) is the gold-standard treatment for this sleep disorder. It involves a therapist who helps the patient identify thoughts, feelings, and behaviors that interfere with sleep, and suggests ways to mitigate them. At Columbia, Alcántara is currently adapting a digital version of CBT-I approved last year by the U.S. Food and Drug Administration—the first of its kind—for Spanish-speaking Hispanic people. “Adaptation is more than translation,” she says. It involves understanding cultural details and family dynamics, such as which family members Hispanics are most likely to trust on medical matters, she says. Next month, she and her team will begin to enroll participants with insomnia in a trial of the culturally adapted CBT-I therapy.
Two months ago, Jean-Louis moved to Miami to launch a Translational Sleep and Circadian Sciences Center at the University of Miami. His new lab aims to probe one factor that could make Black people more vulnerable to poor sleep: There is some evidence that compared with white people, Black people have shorter daily sleep-wake cycles, more readily disrupted by shift work, light pollution, and other factors. “I’ve been puzzled by this for about 20 years,” Jean-Louis says. “We want to get to the bottom of this.” He’s also building a new network of pastors and barbers in the area for his outreach work.
But engaging with communities of color is only a small part of what’s needed, he and others say. Physicians must also play a role, for example. “The training that physicians receive in medical school about sleep is very, very limited,” Brown says. And although the number of sleep specialists has been increasing, “there’s not enough [of them] treating the people that need to be treated,” Johnson adds. “We need more in the right places.”
For the first time, the Department of Health and Human Services earlier this year included improving sleep as one of the main disease prevention goals for the next decade. Brown, who chaired the working group that came up with sleep objectives for the project, called Healthy People 2030, is elated that improving sleep is now a national health priority. She is disappointed, however, that tackling sleep disparities wasn’t ultimately included, despite all the evidence she and others presented to decision-makers. But she’s not deterred. “I am an eternal optimist,” she says. “It may take us until Healthy People 2040, but, you know, we’re pushing.”
Sleep research is starting to influence policy. In 2019, California became the first state to mandate later school times to accommodate children’s and teenagers’ circadian rhythms. And research on shift work has informed guidelines in the aviation industry and for health care workers, aimed at mitigating the negative health effects of sleep disruption.
These policy wins don’t tackle sleep health disparities specifically, but Johnson is quick to point out steps that could. Raising the minimum wage so people don’t have to work multiple jobs and do shift work, implementing noise and light pollution regulations, and improving health care access to people of color through telemedicine are among the ideas Johnson and a colleague proposed in an editorial published last year.
For Alcántara, changing policy to improve the sleep of Black, Hispanic, and other people of color in the country is at the core of fighting structural racism. “If we’re thinking about addressing sleep as a social justice issue, then yes, you have to focus on the policies that are driving who has the luxury of sleeping well and who doesn’t,” she says.