The first study, conducted by the State University of New York (SUNY), analyzed 400,000 respondents from the National Health Interview Surveys between 2004 and 2010. The results revealed that Americans born in the United States report sleeping longer than the recommended amount of seven to nine hours a night. Indian-born Americans reported sleeping six to eight hours a night, and African-born Americans reported sleeping six hours or less.
"We think social desirability might be playing a role in the self-reported data," Abhishek Pandey, MD, the study's lead author, was quoted as saying. "We think that insufficient sleep might be more prevalent in the population than the actual self-report data, but under- or over-reported to project a better image of one's perceived sleep health."
The investigation also showed that foreign-born Americans were less likely than others to report short or long sleep than U.S.-born Americans after adjusting for effects of age, sex, education, income, smoking, alcohol use, body mass index (BMI) and emotional distress.
The second study at the Northwestern University Feinberg School of Medicine involved researchers analyzing the sleep measurements of 439 randomly-selected Chicago men and women, in addition to surveys about sleep quality and daytime sleepiness. They concluded that white participants slept significantly longer than other groups; blacks reported the worst sleep quality and Asians had the highest reports of daytime sleepiness.
"These racial/ethnic differences in sleep persisted even following statistical adjustment for cardiovascular disease risk factors that we already know to be associated with poor sleep, such as body mass index, high blood pressure and diabetes," Mercedes Carnethon, PhD, principal investigator and lead author of the Northwestern study, was quoted as saying. "And we excluded participants who had evidence of mild to moderate sleep apnea. Consequently, these differences in sleep are not attributable to underlying sleep disorders but represent the sleep experience of a 'healthy' subset of the population."
Research indicates that adults who continually sleep shorter or longer than the recommended seven to nine hours can be linked to higher health risks, such as cardiovascular disease, stroke and accidents, and instances of mental or emotional disorders like depression.
The SUNY study goals were aligned with the National Heart, Lung and Blood Institute (NHLBI) Workshop on Reducing Health Disparities: The Role of Sleep Deficiency and Sleep Disorders. The purpose is to better understand insufficient sleep among population subgroups, and to reveal insights about acculturation and miscegenation.