MONDAY, April 3 (HealthDay News) -- Children's behavior and sleep improved after they had a tonsillectomy, whether or not they had sleep apnea before the surgery, according to a University of Michigan Health System study.

And among children in the study who had attention deficit hyperactivity disorder (ADHD) before the surgery, about half did not have it a year after their tonsils were removed.

The 78 children in the study group who had their tonsils removed were much more likely than a comparison group of 27 children to have sleep and behavior problems at the start of the study. However, after the children in the study group had their tonsils out, tests showed little difference between them and the children in the comparison group.

The results appear to support previous research suggesting a link between children's sleep-related breathing problems (snoring, apnea) and daytime behavior problems, the researcher said. However, they added that their findings do not prove cause and effect and that tonsillectomy is not usually a "cure" for ADHD.

"These findings help support the idea that sleep-disordered breathing is actually helping to cause behavioral problems in children, and making them sleepy," study lead author Dr. Ronald Chervin, director of the U-M Sleep Disorders Center and co-leader of the Center for Sleep Science, said in a prepared statement.

"This is one of the first studies to document, using gold-standard measures, that all of these sleep and behavior problems tend to resolve one year after enlarged tonsils and adenoids are removed," Chervin said.

The study is published in the April issue of the journal Pediatrics.

More information

The American Academy of Otolaryngology-Head and Neck Surgery has more about tonsils and adenoids.