ATLANTA — More than a third of U.S. adults sleep less than seven hours a night, and many of them report troubles concentrating, remembering and even driving.

The Centers for Disease Control and Prevention reported the statistics Thursday in two separate studies.

In one study, about 35 percent of people surveyed in 12 states said they slept less than seven hours a night, on average.

The second study based on a national survey found about 23 percent said they had trouble concentrating because they were tired. Another 18 percent struggled to remember things, and 11 percent had difficulty driving or commuting.