Moleendo Stewart cant say for sure whats caused his lifelong sleeping problems. But he has his suspicions.
Theres the childhood spent in loud,restless neighbourhoods in Miami.
You hear people shooting guns all night,dealing drugs, said Stewart,41,who lives in the East Flatbush section of Brooklyn. Sleep experts would point to another factor working against Stewart: He is a black man.
The idea that race or ethnicity might help determine how well people sleep is relatively new among sleep researchers. But in the few short years that epidemiologists,demographers and psychologists have been studying the link,they have repeatedly come to the same conclusion: In the United States,at least,sleep is not colourblind.
Non-Hispanic whites get more and better-quality sleep than people of other races,studies repeatedly show. Blacks are the most likely to get shorter,more restless sleep.
What researchers dont yet know is why.
Were not at a point where we can say for certain is it nature versus nurture,is it race or is it socioeconomics, said Michael A. Grandner,a research associate with the Center for Sleep and Neurobiology at the University of Pennsylvania. But when it comes to sleep,there is a unique factor of race were still trying to understand.
Whatever the cause,doctors say that unlocking the secret to racial sleep disparities could yield insights into why people in some minority groups experience higher rates of high blood pressure,obesity and diabetes.
The latest evidence that race and ethnicity can affect sleep came in June at the annual meeting of the Associated Professional Sleep Societies,held in Boston. In one of two studies on the topic presented there,white participants from the Chicago area were found to get an average of 7.4 hours of sleep per night; Hispanics and Asians averaged 6.9 hours and blacks 6.8 hours. Sleep qualitydefined as ease in falling asleep and length of uninterrupted sleepwas also higher for whites than for blacks.
While those findings are consistent with earlier studies,this one,led by Mercedes R. Carnethon,associate professor of preventive medicine at Northwestern University,adjusted for risk factors like cardiovascular disease,sleep apnea and obesity. Even so,blacks and members of other minorities,who are statistically more prone to experience such problems,still got less and more disruptive sleep than whites.
The idea that differences in work and living conditions can explain the racial sleep disparities is a popular one among sleep experts. But studies that have accounted for those factors suggest a more complex reality.
At least one study suggests that socioeconomic factors affecting sleep are highly specific to race and gender. For example,being divorced or widowed was particularly detrimental to the sleep of Hispanic men. And men of all races who were in relationships slept better than single men,regardless of relationship quality; for women,the quality of the relationship was more likely to affect sleep.
Theres this idea in this country that sleep might not be the most important thing, said Grandner,but we need to be thinking about sleep the same way we think about diet and exercise.