Ethnic differences in sleep quality accompany ethnic differences in night-time blood pressure dipping

Background: African Americans exhibit a smaller nocturnal decrease in blood pressure (BP) than whites, and there are also reports of poorer sleep quality among African Americans. We examined the contribution of sleep quality to ethnic differences in BP dipping in African American and white male and female college students. We hypothesized that African Americans would exhibit blunted nocturnal BP dipping compared to whites, which would be partly accounted for by poorer sleep quality among African Americans. Methods: Forty-three African American and 46 white college students aged 18 to 25 years completed an ambulatory BP protocol that included wrist actigraphy, which was used in conjunction with participant self-reports of sleep times for analyses of sleep quality. Results: Although daytime and night-time BP did not differ according to ethnicity, African Americans had a smaller dip in systolic BP (P < .01), and African American women had a smaller dip in diastolic BP than whites (P <.01). Whites were more likely to be classified as a dipper (71%) than African Americans (41%) (P < .01). African Americans, compared to whites, spent less time in bed, were asleep for a shorter period of time, took longer to fall asleep, exhibited poorer sleep efficiency, and were awakened a higher percentage of the time by the inflation of the BP cuff (F >= 4.85, P < .05). However, sleep quality did not appear to contribute to ethnic differences in diastolic BP dipping. Conclusions: Sleep quality accompanied ethnic differences in systolic and diastolic BP dipping, but did not account for these differences.