Roughly 54 percent of Pacific Islanders, Native Hawaiians and African Americans reported getting at least seven hours of shut-eye a night, compared to 65.5 percent of Hispanics and 67 percent of whites.  

The rate of adequate sleep also varied between states, ranging from a low of 56 percent in Hawaii to a high of 72 percent in South Dakota.  

Not having a job doesn't mean you'll necessary get more sleep, either. In fact, unemployed people are slightly less likely to get enough sleep than those with jobs — 60 percent compared to 65 percent.  

The results of the survey "suggest that employment and higher education might be determinants of healthy sleep," said the CDC in its summary of the findings.  

But the agency also noted that a potentially significant limitation to the data is that it is based on self-reporting of sleep, rather than a precise assessment based on monitoring. It's unclear whether people tend to assess their sleep habits accurately.  

Poor sleep, said the agency, is linked to myriad health problems, including diabetes, heart disease, strokes and depression.  

In addition, the CDC wrote, "Insufficient sleep impairs cognitive performance, which can increase the likelihood of motor vehicle and other transportation accidents, industrial accidents, medical errors, and loss of work productivity that could affect the wider community."