Modafinil is approved by FDA for treatment of all, except:
Modafinil is an FDA approved drug in the treatment of obstructive sleep apnea, shift work disorder and narcolepsy. It is not FDA approved in the treatment of lethargy in major depression. Ref: Sleepiness: Causes, Consequences and Treatment By Michael J. Thorpy, Pages 415-6
Narcolepsy
Shift work syndrome (SWS)
Obstructive sleep apnea syndrome (OSAS)
Lethargy in depression