Ritalin (methylphenidate) is a similar medication also used to treat Attention Deficit Hyperactivity Disorder (ADD or ADHD) and narcolepsy.  It became famous as the medication that most children with ADHD were given to help them pay attention in school.  Ritalin has effects similar to, but more potent than, caffeine and less potent than amphetamines. It has a notably calming and "focusing" effect on those with ADHD, particularly children.  A newer sustained release version (Ritalin SA) is designed to last all day. Ritalin has amphetamine-like properties and is thought to work by stimulating the central nervous system, especially those parts of the brain that help people pay attention.