In the United States, African Americans have higher blood pressure and are at greater risk of hypertension than whites. In addition, African Americans report poorer sleep quality and exhibit a smaller nighttime decrease in blood pressure than whites, a phenomenon called blood pressure "dipping."
"This ethnic difference in blood pressure dipping may help explain why African Americans are at greater risk of hypertension," says Dr. Joel Hughes, Kent State assistant professor of psychology, "as a smaller dip in nighttime blood pressure has been associated with increased left ventricular mass and wall thickness in the heart."
In this month's issue of the American Journal of Hypertension, Hughes and his colleagues examine the possibility that sleep quality may help account for ethnic differences in blood pressure dipping. They found that African-American college students, compared to whites, spent less time in bed, slept for a shorter period of time and took longer to fall asleep. Thus, ethnic differences in sleep quality seemed to accompany ethnic differences in blood pressure dipping; however, it was not shown that these differences in sleep quality caused ethnic differences in nighttime blood pressure.
"Obviously, more research is needed," says Hughes. "There are too few studies of ethnic differences in sleep, and the importance of sleep for health is becoming increasingly recognized."