(Reuters Health) - African Americans who experience everyday discrimination may be sleeping poorly, researchers say.
Among 3,749 black adults participating in a long-term study of heart disease risk factors, experiences with discrimination were a strong determinant of poor sleep, and in particular, short sleep duration and poor sleep quality, the lead researcher told Reuters Health.
"It is important to identify those most at risk, and in our study, women were particularly vulnerable to the effects of discrimination on sleep. Women with the most experiences with discrimination slept on average 30 minutes less at night than those with fewer experiences with discrimination," Dr. Dayna A. Johnson of Brigham and Women's Hospital in Boston added in an email.
Johnson and her colleagues reported their findings at a joint meeting of the American Academy of Sleep Medicine and the Sleep Research Society in Boston.
Between 2000 and 2004 and again between 2008 and 2012, study participants completed the Modified Williams Everyday Discrimination Scale, a questionnaire that asks about the frequency of experiences with everyday mistreatment. For example: How often on a day-to-day basis do you have the following experiences: being treated with less courtesy; being treated with less respect; do people act as if you are dishonest?
Participants also reported their sleep duration and rated their sleep quality from 1 (poor) to 5 (excellent).
At the start, the participants were 55 years old on average, about two-thirds were women, and about 55 percent reported that they slept no more than six hours a night.
From the beginning, discrimination and sleep quality were linked. The association remained constant over time, the research team found.
Compared to participants who reported low levels of discrimination, participants who reported higher levels had 43 percent higher odds of short sleep; they slept 15 minutes less on average per night; and they had lower sleep quality scores.
Women who reported higher levels of discrimination slept 22 minutes less on average compared to those who reported lower levels of discrimination.
"Research has shown that discrimination is strongly related to adverse health outcomes among African Americans," Johnson said. "Based on our findings, it is likely that the influence of stress on sleep is partially attributable to experiences with discrimination. African Americans are continually exposed to experiences of discrimination firsthand, through the vicarious experiences of friends and family, or through the media."
"As a result of the differences in the coping strategies, women may be more affected by experiences of discrimination although they report lower levels and thus have sleep difficulties," she added.
Dr. Michael Grandner, Director of the Sleep and Health Research Program at the University of Arizona College of Medicine in Tucson, told Reuters Health that in earlier research, exposure to racial discrimination was associated with worse sleep, even after taking stress and depression into account.
"Racial and ethnic minorities in the U.S. routinely have worse sleep, and this is important for their overall health and well-being," noted Grandner, who was not involved in the study.
"Knowing that these social-environmental factors play a role in sleep health may persuade clinicians not only to take sleep more seriously, but also to focus more on how they may need to be creative in order to improve health in a social environment that may not be supportive," he said by email.
Johnson said that the study's strengths include the large number of African Americans who participated. She also acknowledges limitations, including that study was confined to residents of Jackson, Mississippi, which limits the generalizability of the results. Also, she points out, people often overestimate how long they’ve slept, so the amounts in the study might not be completely reliable.
Johnson said her team plans to study the issue further using more-reliable sleep data.