Clinic Locations

Woolcock Sleep Clinic
Phone: (02) 9114 0000
Address: 431 Glebe Point Road, Glebe, NSW, 2037 Email: [email protected]
Royal Prince Alfred Hospital
Phone: (02) 9515 6655
Address: Level 11, Main Block, Missenden Road, Camperdown, NSW, 2050
Integrated Sleep Health
Phone: (02) 9331 7546
Address: Suite 1, Level 7, 26 College Street, Darlinghurst, NSW, 2010 Email: [email protected]

Professor Ron Grunstein AM

Professor of Sleep Medicine


Is sleep a mechanism that determines increased risk of high blood pressure and diabetes in African-Americans or does it relate to stress from racial discrimination ?

Posted: August 22, 2015

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