As the United States rolled back the clock an hour this month to observe the end of summer timemany people got a little more sleep than usual – but some not as much as others.
Growing evidence shows that lack of sleep and sleep disorders, such as obstructive sleep apnea, remain more prevalent in black, Asian, and Hispanic or Hispanic communities, and these disparities can have long-term detrimental consequences for physical health, even increasing the risk of certain chronic diseases.
Meanwhile, daylight saving time itself – adopted in the US to reduce electricity consumption by extending daylight hours – has long been controversial in the US.
The American Academy of Sleep Medicine, the Sleep Research Society and other medical groups have advocated ending the practice and called for the adoption of a permanent standard time that would not involve moving forward each spring and falling back each fall.
“Daylight saving time is associated with increased risk of sleep loss, circadian rhythm disruption, and negative health consequences,” said Dr. Beth Malow, professor of neurology and pediatrics and director of the Vanderbilt University Medical Center Sleep Division in Nashville, in a press release this month. She authored a paper, published in September in the journal Sleep, outlining the potential health benefits of adopting a permanent standard time.
In March, the U.S. Senate unanimously passed the Sunshine Protection Act, which would make daylight saving time permanent across the country — meaning there would be no return to “standard time” from early November to mid-March — but the legislation would pass the House and obtain President Joe Biden’s signature before they take effect in November 2023.
Now, some sleep researchers worry about the potential effects that continuing to change standard time twice a year could have on disparities in sleep health.
“Poor sleep is associated with a host of poor health outcomes, including obesity, hypertension, type 2 diabetes, cardiovascular disease, and certain cancers, including breast and colon. Many of these health outcomes are more prevalent in the black population,” said Chandra Jackson, a researcher and epidemiologist at the National Institute of Environmental Health Sciences who has studied racial and ethnic differences in sleep.
“Experimental as well as observational studies have linked sleep to these health outcomes. Therefore, sleep may be an important contributor,” she said. “Fortunately, sleep health is largely modifiable.”
As for the disparities seen in sleep health, it’s not that white adults don’t also experience lack of sleep and its health consequences—but people of color seem to experience them disproportionately more, and that’s believed to be largely due to social systems in the United States.
Sleep allows the body to restore itself on a cellular level. During quality sleep, your heart rate, blood pressure and breathing may rise and fall, which can be important for cardiovascular health, and your body releases hormones that help repair cells and control its use of energy, according to the National Institutes of Health. These hormone changes can also affect your weight.
A study published in October in the journal PLOS Medicine suggests that people age 50 and older who sleep five hours or less a night have a higher risk of several chronic diseases as they age, compared to peers who get a longer night sleep.
Separate research, also published in October in the Journal of the American Heart Association, shows that cardiovascular health guidelines are more effective at predicting a person’s risk of heart disease if they include sleep — and not focus solely on diet and exercise.
Certain physiological processes—such as immune function, cardiovascular health, and memory formation—require certain amounts of sleep. So without enough sleep, the body and brain may not function optimally, said Dr. César Caraballo-Cordovez, a postdoctoral fellow in the Yale-based Center for Outcomes Research and Evaluation, who has studied racial and ethnic differences in sleep duration.
“Short sleep duration has been associated with higher risk of adverse medical events and conditions, including diabetes, obesity, hypertension, heart disease, cognitive decline, and death,” Caraballo-Cordovez wrote in an email, adding that the consensus is that the most adults need at least seven hours of sleep a day.
Still, racial and ethnic disparities in sleep duration appear to be worsening across the United States, according to recent research by Caraballo-Cordovez, Jackson, and colleagues. Their study, published in April in the medical journal JAMA Network Open, found that among more than 400,000 adults in the United States, between 2004 and 2018, the prevalence of short and long sleep duration was consistently higher among those who were black and Hispanic or Latino. . Short sleep is less than seven hours in a day, and long sleep is more than nine hours.
Although there was a significant increase in the prevalence of insufficient sleep across all groups during the study period, the prevalence of short sleep increased by 6.39 and 6.61 percentage points among black and Hispanic or Hispanic adults, respectively, compared to 3 .22 percentage points among white people.
Several social and environmental factors that can disrupt sleep are more common among black and Hispanic or Latino people in the United States, Caraballo-Cordovez said.
“Among these are housing conditions, noise pollution, light pollution, air pollution, stress from various sources – including perceived racial discrimination – and job or working conditions,” he said, adding that the convergence of all these factors may explain why one gets the recommended amount of sleep “may be less common among black adults than among white adults.”
Caraballo-Cordovez and Jackson both emphasize that the reasons behind the racial disparity in sleep warrant more research.
Many social and environmental determinants of health—including living conditions or work schedules that do not support sleep—may stem, at least in part, from historical and persistent forms of structural racism, which Jackson views as “the totality of ways society promotes racial discrimination through mutually reinforcing systems for housing, education, employment, wages, benefits, credit, media, health care and criminal justice.”
Jackson added that she often reflects on how the shooting death of Breonna Taylor in Louisville in March 2020 and the New Year’s Day shooting of George Floyd’s 4-year-old great-niece in Houston both happened as they slept — and how systems of structural racism in the United States can cultivate relationships, that makes such incidents more likely to happen in black communities. “This would require research,” she said.
Examples of structural racism and how it can impact health include the history of discriminatory mortgages and appraisals in the United States, which affect the conditions in which people of color can live; how predominantly white school districts tend to receive more funding than districts serving people of color, affecting the quality of education some people of color may receive; and even how hair discrimination may contribute to some black women using potentially harmful chemical hair products because policies may not allow specific hairstyles at school or in the workplace.
“These policies and practices can produce inequities due to the misallocation of health-promoting or harmful resources across racial groups and, in turn, can reinforce discriminatory beliefs,” Jackson said. “This means that it is believed that discriminatory policies and practices across sectors of society create the physical and social conditions that make it more difficult for black families to get optimal sleep and grow up healthy. Fortunately, these policies and practices can also be changed.”
While more research is needed into the causes of sleep disparities, she said, essentially anything that produces physical and psychological stress is a threat to sleep health, and these stressors tend to be more prevalent in black communities.
In the US Department of Health and Human Services’ Healthy People 2030 plan for the nation, improving health by helping people get enough sleep was listed as a goal, with goals including increasing the proportion of adults with sleep apnea symptoms who were evaluated by a health care provider and increase the proportion of schools that start later in the morning. Improving sleep health has been a national goal in the federal government’s last two Healthy People programs, noted Caraballo-Cordovez, who is not involved in the programs.
But he added that “the impact of strategies focused on improving sleep knowledge and habits—while important and necessary—may be limited if they do not address the persistent barriers that disproportionately prevent black individuals from achieving and maintaining a healthy life.”