TBH, I am really not into taking medicines to sharpen my memory because I'm afraid of some side effects that might result from excessive intake of meds without any therapeutic claims. I'm not saying though that its bad for the health, I'm just more into natural ways of sharpening my memory. Well, you don't need to scrutinize each lessons you have. Take time to read it in order to retain it in your memory, focus and have enough rest in order for you to be prepared well in your exam. The time I usually study is between 4-6 in the morning to start up my day because its the time frame I think that my memory is still fresh and are able to grasp every learnings I take. One thing as well, I have a method which I include in my study habit in order for me to remember lists and that is the mnemonic. Its just simple though, you will actually take the acronyms that you need to memorize specially if its a group or lists of words.