References? Well, if you trust that site as your source of medical information more so than first hand accounts, good luck to you.
Fundamentally, stimulant-resembling drugs of all kinds have side effects, and the detriments are predictably related to the drug's primary function. You can't cheat nature.
That site is half opine and pontification, with a discussion of how to acquire the stuff. If you want to trust that, go ahead.
Basics: Modafinil is a commercial product. Originally for army use, where the long term effects are secondary to the immediate utility. Who's doing the studies? Follow the money. Where does extra energy come from? Not nowhere. Some things don't need medical studies, because humans are not machines and activity out of regular patterns will have side effects.
According to gwern, the detriments are far from clear:
http://www.gwern.net/Modafinil#side-effects
http://www.gwern.net/Modafinil#tolerance