Did you know that Methylphenidate (Ritalin) is a medication prescribed for individuals (usually children) who have an abnormally high level of activity or attention-deficit hyperactivity disorder (ADHD). According to the National Institute of Mental Health, about 3 to 5 percent of the general population has the disorder, which is characterized by agitated behavior and an inability to focus on tasks. Methylphenidate also is occasionally prescribed for treating narcolepsy. Methylphenidate is a central nervous system (CNS) stimulant. It has effects similar to, but more potent than, caffeine and less potent than amphetamines. It has a notably calming effect on hyperactive children and a "focusing" effect on those with ADHD.