U-M’s four-year study, published today in the journal Pediatrics, found half of children who suffered from hyperactivity and attention disorders before the surgery no longer had the condition a year afterward.

Researchers believe enlarged tonsils can cause sleep problems, and sleep problems can cause daytime behavior troubles.

While the study doesn’t prove a tonsillectomy is a cure for attention deficit hyperactivity disorder, removing enlarged tonsils can eliminate the cause of behavior disorders for some, said Dr. Ronald Chervin, a University of Michigan sleep disorder researcher and author of the study.

Tonsils are designed to catch incoming germs that can cause infections, according to the American Academy of Otolaryngology — Head and Neck Surgery.

Hanaan Abouzahr was 10 when she had hers removed, and her parents, Kristine and Saad Abouzahr, volunteered to participate in the study.

"I’m not the oddball anymore," Hanaan said.

From the time she turned 8, Hanaan snored so loudly that her sisters kicked her out of the bedroom they shared in their Ann Arbor home. Hanaan slept in a downstairs guest room. A bright girl, her grades suffered and her teachers complained she wasn’t paying attention. She was unfocused at home. Sometimes she dozed in class.

Now 11, and without tonsils, Hanaan believes she is a new person.

"It makes me feel a lot less self-conscious. I have more energy. It makes me feel a lot better about myself," she said.

More than 1 million U.S. tonsillectomies were performed yearly during the 1950s and ’60s. But parents’ increased involvement in surgical decisions, plus antibiotic drugs that effectively fight throat infections, have sliced that figure to probably under 400,000, said Dr. Susan Garetz, who specializes in ear, nose and throat surgery for children at U-M. However, small studies and personal experiences dating to the late 1990s have convinced many doctors to consider tonsils when treating kids with behavioral problems. Garetz said parents are surprised when doctors ask, "Does this child snore?" But some who are looking for alternatives to drug therapy for their hyperactive children are embracing tonsillectomy as an alternative worth trying.

Chervin said 91 percent of 78 children in his study who had tonsillectomies had the surgery to deal with snoring, not sore throats.

A recent survey of Michigan doctors came up with different figures. It said 43 percent of the tonsillectomies prescribed for children were to treat sore throats, and 58 percent were for sleep-related breathing problems, poor attention and poor school performance, Garetz said.

Still, the medical world has conducted no large-scale studies. The latest U-M study of 105 children from 1999 through 2004 is the most comprehensive so far. A follow-up has been launched to study at least 100 more children having their tonsils removed in Ann Arbor.

Chervin said studies of adults are easier. They describe sleepiness and understand its effects.

"Children don’t," Chervin said. "They also don’t express the effects of sleep disorder as well. Children have such a strong desire to stay awake and learn that they cause their own commotion to stay awake.

"This study takes us a step closer to understanding the relationship between snoring and sleep apnea in children and the incidence of inattention, hyperactivity and other problems that may stem from sleepiness.

"If you have a child with hyperactivity and inattentive disorders, you and your pediatrician should not ignore sleep disorders as a possible primary cause," he said.

Hanaan said everyone in her house sleeps better now.

And while she never noticed her snoring, "it must have kept me from getting good sleep."

"I feel way more awake and energetic now," she said. "When someone turns on a TV, I don’t get distracted so easily. I can keep studying, keep concentrating. I don’t take naps like I used to. I Rollerblade and I’m way more active than I was."