NEW YORK (Reuters Health) - Preschool-aged children with sleep problems are more likely to have behavior problems and poor health-related quality of life than kids without sleep difficulties, a new study from Australia shows.

One-third of the 4- to 5-year-old children in the study had mild, moderate or severe sleep problems, Dr. Harriet Hiscock of the Royal Children's Hospital in Victoria and colleagues report in the medical journal Pediatrics. Given how common these problems are, Hiscock and her team warn, they could "adversely affect the transition to school of very large numbers of children."

However, the researchers add, these problems are probably easily treatable.

Sleep problems in school-aged kids have been shown to increase the risk of behavior problems, poor performance in school and low health-related quality of life, the researchers note. On the other hand, less is known about the effects of sleep problems in preschool-aged children.

To investigate, Hiscock and her colleagues looked at 4,983 families participating in a national study of children's health. Nearly 20 percent of the children had mild sleep problems, while almost 14 percent had moderate to severe sleep problems. Problems included waking in the night, reported in 18 percent of kids, and difficulty falling asleep, in about 13 percent.

Children with moderate to severe sleep problems were 12 times more likely to have been diagnosed with attention deficit-hyperactivity disorder (ADHD), while they were 37 percent more likely to have suffered an injury requiring medical attention. Difficulty falling asleep at night and being tired after waking up in the morning were the sleep difficulties most strongly linked to behavior problems and poor health related quality of life.

The researchers found no association between sleep problems and children's vocabulary and preliteracy skills.

"Proven strategies" are available to help children who have difficulty falling asleep, for example establishing a "good 'sleep hygiene' routines," while morning sleepiness can usually be addressed by making sure the child sleeps longer, Hiscock and her colleagues advise.

Managing sleep problems during the preschool age "may in turn improve a child's quality of life, behavior, and injury risk," they conclude.