Prescription stimulants are drugs that improve states of alertness and wakefulness. They stimulate both the central nervous system and sympathetic nervous system and often produce euphoric feelings. They help patients suffering from ADD or ADHD and are also used to treat narcolepsy and other sleep disorders. The most used stimulants are Ritalin, Concerta, Adderall and Adderall XR; there are also some new drugs called eugeroics. Modafinil and adrafinil, marketed as Provigil and Olmifon belong to this class.