Racial differences in heart rate variability during sleep in women: the study of women across the nation sleep study.
BACKGROUND
Heart rate variability (HRV) differs markedly by race, yet few studies have evaluated these relationships in women, and none have done so during sleep (sHRV).


METHODS
We addressed these gaps by examining sHRV in women of African American, Chinese American, or European American origin or descent (mean [standard deviation] age = 51.2 [2.2] years).


RESULTS
HRV during Stage 2 non-rapid eye movement (NREM) and rapid eye movement (REM) sleep differed significantly by race after adjusting for possible confounders. Normalized high-frequency HRV was significantly lower in European American compared with African American and Chinese American participants (European American NREM = 0.35 [0.01], REM = 0.23 [0.01]; African American NREM = 0.43 [0.02], REM = 0.29 [0.02]; Chinese American NREM = 0.47 [0.03], REM = 0.33 [0.02]; p values <.001). European Americans also exhibited higher low-to-high-frequency HRV ratios during sleep compared with African American and Chinese American women (European American NREM = 2.42 [1.07], REM = 5.05 [1.07]; African American NREM = 1.69 [1.09], REM = 3.51 [1.09]; Chinese American NREM = 1.35 [1.07], REM = 2.88 [1.13]; p values <.001).


CONCLUSIONS
Race was robustly related to sHRV. Compared with women of African American or Chinese American origin or descent, European American women exhibited decreased vagally mediated control of the heart during sleep. Prospective data are needed to evaluate whether sHRV, including race differences, predicts cardiovascular disease.
Department of Psychiatry, University of Pittsburgh School of Medicine, Suite E-1101, 3811 O'Hara Street, Pittsburgh, PA 15213. hallmh@upmc.edu.
Martica H
MH
Hall
Kellie
K
Middleton
Julian F
JF
Thayer
Tené T
TT
Lewis
Christopher E
CE
Kline
Karen A
KA
Matthews
Howard M
HM
Kravitz
Robert T
RT
Krafty
Daniel J
DJ
Buysse
D001741:Black or African American / Q000706:statistics & numerical data*; D000704:Analysis of Variance; D001213:Asian / Q000706:statistics & numerical data*; D001341:Autonomic Nervous System / Q000502:physiology; D002318:Cardiovascular Diseases / Q000208:ethnology; D015986:Confounding Factors, Epidemiologic; D004562:Electrocardiography / Q000379:methods; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008875:Middle Aged; D017286:Polysomnography / Q000379:methods; D056152:Respiratory Rate / Q000502:physiology; D012307:Risk Factors; D057566:Self Report; D020181:Sleep Apnea, Obstructive / Q000453:epidemiology / Q000503:physiopathology; D012894:Sleep Stages / Q000502:physiology*; D012907:Smoking / Q000453:epidemiology; D044465:White People / Q000706:statistics & numerical data*
autonomic tone; cardiovasular disease; heart rate variability; race; sleep; women