Halder and colleagues have just published a paper in SLEEP examing the realtionship between sleep patterns and race using methods to determine genetic ancestry instead of self-identification which may be inaccurate.
They used a community-based sample of 70 African Americans (mean age of 59.5 y) and 101 Caucasian/European-Americans (mean age of 60.5 y) using a panel of 1,698 ancestry informative genetic markers and ranged from 10% to 88% (mean of 67%)—a wide range typically expected for a genetically admixed population. In-home sleep studies measured sleep duration, sleep efficiency, and indices of sleep depth including percent visually scored slow wave sleep (SWS) and non-rapid eye movement (NREM) EEG delta power were used as the primary sleep variables.
They found a higher percentage of African ancestry was associated with lower percent SWS in African Americans and explained 11% of the variation in SWS after adjusting for various covariates. Similarly, a higher percentage of African ancestry was associated with lower NREM EEG delta power and explained 10% of the variation in delta power. No such associations were observed for sleep duration or sleep efficiency.
The paper authors suggest that as SWS is critical to restorative physiological processes that occur during sleep, these racial differences may realte to poorer cardiometabolic health in African-Americans. Previous authors have raised the possibility that stress may reduce slow wave sleep. Psychological stress attributable to racial discrimination (i.e. specific discrimination attributed to perceived racism) but not unfair treatment or everyday discrimination in general has been suggested as a mediator of racial differences in SWS. These new results indicate that to sort out the impact of racial difference in SWS will require an examination of genetic causes in addition to behavioral, environmental, and/or psychosocial factors. It is certainly possible that sleep and ancestry may interact to influence cardiometabolic risk. It is also possible that genetic ancestry is a predictor of both SWS and hypertension, a common molecular mechanism may govern both physiological processes.
African Genetic Ancestry is Associated with Sleep Depth in Older African Americans
Indrani Halder, PhD1; Karen A. Matthews, PhD2; Daniel J. Buysse, MD2; Patrick J. Strollo, MD1; Victoria Causer, MD1; Steven E. Reis, MD1; Martica H. Hall, PhD2
1Department of Medicine, University of Pittsburgh, Pittsburgh, PA; 2Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA