I tried modafinil for about a month -- maybe a bit longer; I don't remember -- and believe it had the desired effect (although I'm not convinced that wasn't a placebo). I felt more focused and, importantly, less prone to anxiety and depression, without the unstable skittishness that, say, caffeine gives me. (That said, it made my pee smell rather funky!) After researching as much as I could, I felt the risk was acceptable. The only reason I didn't continue my "experiment" was that it's a bit too expensive for the relatively mild improvements. (e.g., A good holiday, as the article mentioned, has a similar effect.) I considered trying to get it on prescription -- as it definitely seemed to help with my anxiety -- but felt that, besides that being off-label and therefore unlikely to be approved, it would be an somewhat unethical use of NHS resources!