TUESDAY, June 14 (HealthDay News) -- Preschoolers who don't get enough sleep are more likely than other children to be hyperactive and inattentive by the time they reach kindergarten, according to a new study.

Although attention-deficit/hyperactivity disorder (ADHD) is typically not diagnosed before age 5, the study's authors said the onset of ADHD-like symptoms, such as inattention, hyperactivity and impulsivity, often occurs earlier.

"These findings suggest that some children who are not getting adequate sleep may be at risk for developing behavioral problems manifested by hyperactivity, impulsivity, and problems sitting still and paying attention," study lead author Erika Gaylor, senior researcher for SRI International, an independent, nonprofit research institute in Menlo Park, Calif., said in a news release from the American Academy of Sleep Medicine.

In conducting the study, researchers examined the sleeping patterns (based on parental accounts of bedtimes and wake times) of roughly 6,860 children, taking into account their gender, ethnicity and family income. Parents were also asked to evaluate ADHD-like symptoms in their children, including attention and task persistence as well as hyperactivity and impulsivity.

"Children who were reported to sleep less in preschool were rated by their parents as more hyperactive and less attentive compared to their peers at kindergarten," Gaylor said.

However, inattention and hyperactivity in the preschool years was not a predictor of sleep duration in kindergarten, the researchers said.

The findings were scheduled for presentation Tuesday at a meeting of the Associated Professional Sleep Societies in Minneapolis.

In a previous study, Gaylor reported that having a consistent bedtime was the most reliable predictor of positive developmental outcomes by age 4.

Because the study is slated to be presented at a meeting, the findings should be considered preliminary until published in a peer-reviewed journal.

More information

The U.S. Centers for Disease Control and Prevention provides detailed information on the symptoms and diagnosis of ADHD.