During the exam period i decided to take ritalin because some of my friends advised, that was to increase my attention and concentration during the test period. First 2 days i indeed felt more concentrated and aware of everything but i couldn’t sleep, all i got for 4 days is 2-hour sleep during the entire night. Then i became exhausted. It's a bad idea to take ritalin, although my friend said there are doing fine. Could it be because of something else? Maybe i loss sleep because of the stress associated with exams. Also, it game me pack pan, starting from the neck all the way down, i don't know... I think it is the last time using concentration drugs.