How many of you feel as though you get enough sleep every night? Raise your hand. Anyone?
By now, most of us know that not getting the recommended seven to nine hours of sleep nightly can affect our health in a variety of ways. And perhaps you know that race and ethnicity matter when it comes to how many hours we sleep. Blacks tend to get less sleep than other racial groups.
The researchers at the Northwestern University Feinberg School of Medicine know this, and when they started to crunch the numbers for their Chicago Area Sleep Study, they weren't surprised to learn that the average sleep duration for white participants was 7.4 hours per night compared with 6.8 hours for blacks.
What researchers hadn't expected was that Asian-American participants, who are similar to whites in terms of education levels and socioeconomic profile, had sleep patterns more in line with those of blacks and Hispanics, who averaged seven hours of sleep per night.
Mercedes Carnethon, the lead author of the study, said the findings were surprising.
"It's curious because the cardiovascular risk profiles and demographic characteristics commonly associated with short sleep are even better in Asian-Americans than whites, yet Asian-Americans have significantly shorter sleep," said Carnethon, associate professor of preventive medicine at Feinberg.
The study, funded by the National Heart, Lung and Blood Institute, set out to understand how lack of sleep affects people who may not get the recommended hours of shut-eye per night but haven't been diagnosed with a sleep disorder, such as sleep apnea or insomnia.
Because sleep patterns vary according to race and ethnicity, the researchers recruited a diverse group of participants for the study, conducted from 2009 to 2011: 112 Asian-Americans, 137 whites, 156 blacks and 112 Hispanics. (About 60 percent of the participants were women.)
Participants were given equipment that they took home and used to measure sleep patterns for seven days. Afterward, researchers logged the participants' height, weight, blood pressure and blood cholesterol and took a complete medical history from each.
Researchers found that blacks fared worst in terms of sleep duration and quality of sleep. Carnethon said one theory behind the disparity is that a large portion of the study's black participants live in beleaguered communities on the West Side, where restful sleep may be harder to come by.
But why the disparity with the Asian-Americans, about half of whom were of Chinese descent and the remainder of Japanese and Korean descent?
Carnethon said it's not clear since they tended to not have the risk factors associated with poor sleep patterns.
For example, obese people tend to be shorter sleepers. But with a body mass index of 23, the Asian-American participants had the lowest BMI of all the groups. The BMI was 25 for whites and 28 for blacks and Hispanics.
Smokers also struggle with sleeping the recommended hours but, in the study, fewer Asian-Americans smoked than whites.
People with high blood pressure and diabetes tend to have trouble sleeping as well. And here is where things got even more complicated. The Asian-American participants had hypertension at levels double that of whites. Their diabetes levels were also higher than in whites, although not higher than in blacks and Hispanics.
"It's interesting in the Asian community that despite the leaner bodies, they have higher rates of diabetes, particularly people of Chinese, Filipino and South Asian (descent)," Carnethon said. "And you think: Why is that when they don't have the body fat? Maybe it's the way they're sleeping."
She said what's also puzzling is that neither high blood pressure nor diabetes would likely cause short sleep patterns. Rather, they would be a consequence.
She said follow-up research on Asian-Americans, a group whose sleep patterns haven't been studied as much, might focus on depression, crowded households and job stress to find possible answers.
In the end, how well and long we sleep is an important subject for everyone. Among the many sleep studies, a recent one released by the University of California at San Francisco, found that older people who have trouble sleeping may be at a greater risk of developing Alzheimer's disease or dementia later in life, compared with folks who sleep more soundly.
Carnethon said that although sleep remains a popular topic, it's viewed as a luxury for too many people. And that's a problem.
"Maybe we need 'get-regular-sleep' campaigns that would be like anti-smoking campaigns," she said. "And maybe the campaigns need to target the groups more likely to have less sleep."