<prompt> Modafinil is approved by FDA for treatment of all except :Obstructive sleep apnea syndrome OSASShift work syndrome SWSNarcolepsyLethargy in depression  <response>: Modafinil Provigil :Modafinil is an oral drug that is used for improving wakefulness in patients with excessive sleepiness.Modafinil is used to promote wakefulness in patients with excessive sleepiness associated with :Narcolepsy.Obstructive sleep apneahypopnea syndrome andShift work sleep disorder.The exact mechanism of action of modafinil is not clear. It seems that modafinil increases the release of monoamines specifically the catecholamines norepinephrine and dopamine from the presynaptic terminals. However, modafinil also elevates hypothalamic histamine levels in contrast to amphetamine-like stimulant which only releases catecholamines, but not histamine. 