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Racial Differences in Heart Rate Variability During Sleep in Women:
The Study of Women?s Health Across the Nation Sleep Study
Hall MH, Middleton K, Thayer JF, Lewis TT, Kline CE, Matthews KA, Kravitz HM, Krafty RT, Buysse DJ
(Psychosomatic Medicine, 75:783-790, 2013)

Although the leading cause of death for women in the United States is cardiovascular disease, little is known about the pathways through which sleep may influence cardiovascular disease in women.  Dr. Martica Hall and her colleagues used heart rate variability to examine the dynamics of the autonomic nervous system during sleep in a large sample of midlife women.  This study examined the contribution of race to heart rate variability during sleep.  The study?s second author, Dr. Kellie Middleton, pictured above with Dr. Hall, assisted with this study as part of her research education while she was a medical student at the University of Pittsburgh School of Medicine.

Participants were drawn from the Study of Women?s Health Across the Nation (SWAN) Sleep Study and included 368 participants who were self-identified as African American, Chinese American or European American.  Measures of sleep and heart rate variability were derived from polysomnographic sleep studies conducted in participants? own homes.  

Dr. Hall and her colleagues found that race was robustly related to heart rate variability during sleep.   European American women exhibited decreased heart rate variability during sleep, compared to African American or Chinese American women.  These effects were independent of other sociodemographic, psychological, behavioral, and medical factors known to influence sleep and heart rate variability.  Moreover, race effects on heart rate variability during sleep were unrelated to sleep disordered breathing. Although the heart rate variability profile during sleep observed in Chinese American women is consistent with their generally low risk for cardiovascular disease, study results for African American participants are paradoxical given their increased risk for cardiovascular events, including myocardial infarction and stroke.

Based on these results, the researchers concluded that heart rate variability in women fluctuates as a function of sleep and is modified by race.  What causes race differences in heart rate variability during sleep and their importance to cardiovascular risk and disease course remain to be determined by future studies.

Contributors:  
Martica H. Hall, PhD; Christopher E. Kline, PhD; Karen A. Matthews, PhD; Daniel J. Buysse, MD (Department of Psychiatry, University of Pittsburgh)
Kellie Middleton, MD, MPH (University of Pittsburgh School of Medicine)
Julian F. Thayer, PhD (Department of Psychology, Ohio State University)
Tené T. Lewis, PhD (Rollins School of Public Health, Emory University)
Howard M. Kravitz, DO, MPH (Departments of Psychiatry and Preventive Medicine, Rush University Medical Center)
Robert T. Krafty, PhD (Department of Statistics, Temple University)

The results of this investigation were published in Psychosomatic Medicine.  Click here for a link to the abstract.