NEW YORK -- Do you have trouble concentrating or paying attention? Are you restless? You may have attention deficit hyperactivity disorder. A lot of people think ADHD only affects kids -- but adults can have it, too.

All of us feel a bit impulsive, disorganized, or restless some time in our lives. But when those feelings are constant and severe, they may be symptoms of a real medical illness.

"I'm one of those people who burns out the remote," said Phyllis Goldman, an ADHD sufferer. "I channel-surf for hours and watch commercials for three hours every night because I can't concentrate on anything."

It took doctors nearly 50 years to correctly diagnosis Goldman with ADHD.

"ADHD used to be thought of primarily as a disorder of childhood," said Dr. Lenard Adler of New York University Medical Center. "Symptoms of inattention, distraction, trouble keeping things in mind, impulse dysregulation, calling out in class, somehow were magically supposed to go away as children went through adolescence. We now know that most of the time they don't."

"Nobody ever evaluated me for this," Goldman said. "I find that it makes me very angry sometimes to think that I could have done a lot more, because I had a problem in school."

Studies show about 4 percent of adults have ADHD -- that's about 8 million Americans. Most of the time, a doctor never makes the diagnosis.

Common symptoms of adult ADHD include:

Short attention span
Disorganized
Restlessness
Depression
Low energy level

"It makes relationships very hard, it makes working very hard, it makes keeping your home life and your personal business very difficult," she said.

"[ADHD patients] are more likely to be divorced or separated; they're more likely to underperform on the job and have more ADHD symptoms on the job," Adler said.

Now that Goldman has been diagnosed ADHD, she's taking appropriate medication and sees a dramatic improvement.

"[The medication] helps me stay focused," she said. "I'm able to take things in. I'm functioning much better at work. I'm more organized, I'm getting along better with people. My frustration level is way down. My whole life is improving."

Some of the medications that are recommended for adults with ADHD include Ritalin, Concerta and Metadate.