No but I swear by something else. Go to youtube and search for the uploader relaxingrecords (I think). it’s music to study and concentrate by, mostly classical, but selected to encourage deep concentration. I had to pass two PhD final exams in economics in late May and also study for the CFA and had little study time (massive workload at the time didn’t help), so I REALLY needed to find a way to focus. I studied while listening to this music and swear it helped. On the exam itself, when i started to get stressed over a question i thought I couldn’t answer, I recalled the music and I think it helped to slow and calm my mind a bit. I passed the finals and the CFA and don’t think I would have been able to get such focus without this. Could be a placebo effect, but I think it worked for me and i’ll do this again next time I need to focus.
I went to a hypnotherapist but it didn’t really help. For some reason though, I got great pleasure out of paying him double his bill and washing his car afterward.