BACKGROUND: Attention Deficit Hyperactivity Disorder (ADHD) is a condition that usually begins in preschool or early school years. Children with the disorder have a difficult time controlling their behavior and paying attention. Researchers estimate between 3 percent and 5 percent of children (about 2 million) in the United States have ADHD. That means a classroom of 25 to 30 children is likely to have at least one with ADHD.

SYMPTOMS: The main symptoms of ADHD are inattention, hyperactivity and impulsivity. Symptoms of ADHD will appear over the course of many months. Often, the symptoms of impulsiveness and hyperactivity precede those of inattention, which may not emerge for a year or more. Different symptoms may appear in different settings, depending on the demands the situation may pose for the child's self-control. According to the most recent version of the Diagnostic and Statistical Manual of Mental Disorders, there are three patterns of behavior that indicate ADHD. People with ADHD may show several signs of being consistently inattentive. They may have a pattern of being hyperactive and impulsive far more than others their age, or they may show all three types of behavior. This means that there are three subtypes of ADHD recognized by professionals. These are:

•Predominately hyperactive-impulse type -- does not show significant inattention

•Predominately inattentive type -- does not show significant hyperactive-impulse behavior

•Combined type -- displays both inattentive and hyperactive-impulse symptoms

(Source: The National Institute of Mental Health)

COULD IT BE SOMETHING ELSE? A growing number of doctors around the country say ADHD is commonly being misdiagnosed. Many children diagnosed with ADHD may actually have a sleep disorder instead. Thomas Burns, Psy.D., a neuropsychologist at Children's Healthcare of Atlanta, says: "Many of the kids with a sleep disorder will present with inattention. They'll have fatigue. They may even look like a child who has ADHD, but in fact, it's related to their sleep, and their problems that they're having." A sleep analysis study can determine whether it's a sleep disorder or ADHD that the child is suffering from. Common sleep disorders may include sleep apnea or narcolepsy. These disorders aren't always treated with medication. Procedures such as removing the tonsils and adenoids or a special machine called a CPAP can clear the obstructed airway for kids with sleep apnea. In other situations, changing sleep habits and bedtime routines can improve sleep at night so much that the child will be well-rested and alert during the day. Gary Montgomery, M.D., a pediatric sleep medicine specialist at Children's Healthcare of Atlanta, says the bottom line is you shouldn't assume your child has ADHD. "The really important message for parents is if there's any problem during the day that might sound like attention deficit, then think about your child's sleep," he says.