You don't want to read the study... But if you do, there's a brief inlook here:
http://www.holah.co.uk/summary/freud/
Argh, it has the giraffe dream there! I just don't see how Freud saw that in the dream

I don't think the study is real. It's too farfetched, plus when Freud told Hans about the study when he was about 18, the guy didn't remember any of it. Oh, and Freud used cocaine much of his life, and even wrote a paper on it...