ChEBI: (S)-modafinil is a 2-[(diphenylmethyl)sulfinyl]acetamide that has S configuration at the sulfur atom. The racemate comprising (S)-modafinil and its enantiomer, armodafinil, is known as modafinil and is used for the treatment of sleeping disorders such as narcolepsy, obstructive sleep apnoea, and shift-work sleep disorder. The enantiomers have similar pharmacological actions in animals. It has a role as a central nervous system stimulant and a eugeroic. It is an enantiomer of an armodafinil.