Sleep disorders strike people from all walks of life, but seem to be more common among African-Americans. And wealth or social status is not necessarily a protection: The most sleep-deprived group of U.S. adults is black professionals, according to a new study published in the American Journal of Epidemiology.

Getting less than seven hours of sleep might have long-term consequences beyond a heavy reliance on caffeine. Poor sleep habits have been tied to a myriad of health problems: diabetes, obesity, and coronary heart disease, just to name a few.

"With increasing numbers of blacks entering professional and management roles in numerous industries, it is important to investigate and address the social factors contributing to the short sleep disparities in blacks compared with whites in general, and particularly in professional settings," Harvard School of Public Health researcher Chandra Jackson said in a statement.

Jackson and her colleagues analyzed data on more than 136,000 U.S. adults that answered the National Health Interview Survey conducted by the U.S. Census. One of the questions in the NHIS asks people to self-report their average sleep duration. Of the sample used in the current study, 30 percent were “short sleepers,” meaning they slept less than the optimal 7 hours a day.  31 percent of study subjects were optimal sleepers, and 39 percent of subjects were “long sleepers,” snoozing for more than 7 hours every night.

When they ran the numbers, the researchers saw that 37 percent of black respondents were short sleepers, as compared to 28 percent of white respondents. The disparity was even higher when people worked at professional or managerial positions in their industries; 42 percent of black professionals experience short sleep, as compared to 26 percent of white professionals.

“Short sleep generally increased with increasing professional responsibility within a given industry among blacks but decreased with increasing professional roles among whites,” the authors wrote.

Various social factors likely explain this phenomenon, the researchers say. African-Americans are much more likely to work the night shift and have long working hours. Working irregular hours can disrupt a person’s circadian rhythm and increase cravings for salty and sweet foods as a consequence.

“Compared with whites, blacks are also more likely to report general job stress, to experience objective and perceived discrimination, to work in positions with low control/high demand and that involve low decision-making power, to work multiple low-wage jobs, and to live in poverty despite being employed,” Jackson and colleagues wrote.

Trying to reconcile a strong work ethic with the handicaps of racism may lead to these sleep disruptions and other health problems, the authors speculate. Jackson and her colleagues refer to the phenomenon as “John Henryism.” Songs and ballads tell how the black American folklore hero John Henry, who drove steel with a hammer, beat a steam-powered drill in a contest he devised after its introduction threatened to replace the human labor. Henry saved the jobs of his fellow railroad workers, but died at the moment of his victory. Similarly, it appears that many black professionals driven to succeed may be run ragged. 

SOURCE: Jackson et al. “Racial Disparities in Short Sleep Duration by Occupation and Industry.” American Journal of Epidemiology published online 9 September 2013.