A new study led by researchers from Brigham and Women’s Hospital looked at data from white, Black, Chinese, and Hispanic adults in the United States, and measured different aspects of their sleep using actigraphy, self-reports, and polysomnography. The team found clear differences, with the highest sleep health observed in the white group and the lowest in the Black group. Chinese and Hispanic groups had intermediate outcomes. In looking at what was driving these sleep health disparities, investigators found that Black and Hispanic adults were less likely than white adults to experience adequate sleep duration and more likely to experience high night-to-night variability in when they went to bed. Their results are published in The American Journal of Epidemiology.
“Insufficient sleep has been connected over time with mortality, cardiovascular disease and quite a few unfavorable health outcomes,” says Joon Chung, PhD, a research fellow in the Division of Sleep and Circadian Disorders at the Brigham, in a release. “If we could close the gap in sleep, we may be able to begin to close the gap in other outcomes, like mortality and cardiovascular disease, and indirectly help reduce health disparities.”
The new study used data from the Multi-Ethnic Study of Atherosclerosis (MESA) to compare groups of US white, Black, Chinese, and Hispanic adults. The research team found this dataset specifically beneficial because of its focus on racial-ethnic minorities. Moreover, while many sleep studies rely solely on self-reports, MESA’s additional use of actigraphy and polysomnography ensured a comprehensive dataset.
“Using MESA data from over 1,700 adults, we created a global sleep health risk score composed of measures of sleep duration (how much we sleep), sleep timing (when we sleep), sleep quality (self-reported and objectively measured sleep depth—slow wave sleep), sleep continuity, and sleep apnea,” says Susan Redline, MD, MPH, of the Brigham’s Division of Sleep and Circadian Disorders, in a release.
Using the sleep measures, the team found that the largest differences in sleep health were between white and Black adults. Moreover, Black and Hispanic adults were less likely to experience adequate sleep duration compared to white adults. Black and Hispanic adults were also more likely to experience variability in night-to-night sleep patterns. Large racial-ethnic disparities were found when analyzing irregular timing and duration, insufficient duration and fragmented sleep. The research team took a special interest in sleep irregularity and found it to be a driving force in these disparities.
“Irregularity, in theory, is intervenable and fixable. We actually have interventions for regularity in sleep hygiene,” says Chung. “So, I think that’s one of the more exciting parts about this because it’s not just identification of the problem, but also that there are some pre-existing solutions.”
The authors note that sleep is holistic and therefore there are many factors that contribute to good sleep health. Black, Hispanic, and Asian adults are more likely to experience risk factors for poor sleep such as unstable work schedules, less safe neighborhoods, environments with more light or noise, and increased stress. The researchers hope that this study will heighten awareness of racial-ethnic sleep disparities among clinicians when treating non-white patients.
“Our research demonstrates that there is a high prevalence of sleep problems among non-white populations and suggests that clinicians should consider screening everyone for sleep issues because these are intervenable factors that then may drive other health disparities,” Redline says.
While the MESA data is comprehensive, the adults studied are only from six US cities. The authors recognized that the factors affecting racial-ethnic minorities in sleep could differ by geography, making greater coverage a key next step. The study was also exclusive to older adults with a mean age of 68.3 years. The researchers noted that looking at a younger population could reveal different patterns. Moving forward, the team would also like to see more specific research on under-studied populations.
“This research shows that global sleep health can help track and inform health disparities,” Redline says. “Moreover, the findings underscored the need for public health efforts to improve adequate and consistent sleep for minority groups to reduce sleep health disparities and thus improve health.”