Perceptions of racism may cause loss of sleep and perhaps loss of sleep may also impact perceptions of racism.

A new study has found that self-reported sleep disturbance correlated to perceived racism, which was increased by 61 percent after adjusting for socioeconomic factors and symptoms of depression. A similar relationship between perceived racism and daytime fatigue was no longer significant after additional adjustment for depressive symptoms.

The study involved an analysis of data from the 2006 Behavioral Risk Factor Surveillance System, which is administered by the Centers for Disease Control and Prevention. The world's largest, ongoing telephone health survey, it is an annual, state-based, random-digit-dialed survey of American adults. Researchers analyzed responses from 7,093 people in Michigan and Wisconsin, which were the only states to collect data on both sleep and racism.

Perceived racism was assessed with the question: "Within the past 12 months when seeking health care, do you feel your experiences were worse than, the same as, or better than for people of other races?" Responses were dichotomized as either "worse" or "same or better." Respondents were classified as having sleep disturbance if they reported having difficulty sleeping at least six nights in the past two weeks.

"This study found that an environmental stressor that exists purely at the social level - perceived racial discrimination - had a hand in how likely a person was to experience disturbed sleep," said lead author Michael A. Grandner, PhD, Postdoctoral Fellow at the Center for Sleep and Circadian Neurobiology at the University of Pennsylvania in Philadelphia, Pa. "The most surprising finding in this study was that individuals who perceived racial discrimination were more likely to experience sleep difficulties, and it did not matter if they were Black or White, men or women, rich or poor, or even if they were otherwise depressed or not, since these were adjusted for in the statistical analysis.

Grandner noted that people who experience racial discrimination are more likely to have poor mental and physical health. The results suggest that sleep may be an important pathway linking discrimination with health problems.

"Sleep is essential for health, and many processes in our body depend on sleep to function properly," he said. "Disturbed sleep may be a factor that contributes to heart disease, diabetes, weight gain, depression, cancer, auto accidents, poor performance, and many other important outcomes. And even though sleep is a biological process, it can be affected by social environments."

The research was presented today at SLEEP 2011, the 25th Anniversary Meeting of the Associated Professional Sleep Societies.