You guys are going to have a real tough time in psych rotations. A lot of the things people are saying here are pretty hateful towards people's conditions, and I expect better from people who want to be doctors.
Here's what I can say on it, as someone with ADHD, who managed for a long time without stimulants (but with caffeine self medication), and have found them useful as well:
With actual ADHD, the stimulants actually make you calmer. Having had ADHD for my whole life, diagnosed officially for most of college, and only started taking a stimulant rx for them senior year, its kind of remarkably actually. It really reduced stress as well, I felt much more ordered in my life. That alone is worth taking them, for the same reason we give them to 3rd graders. My grades have been pretty good on and off stimulants, they helped some, but not because of being able to stay up all night; I can do that with caffeine and willpower. Actually did more all nighters without amphetamines than I have with; I really love the peace of the middle of the night, and the feeling of clarity from being in the sun the next day.
It's not that you can't dose up on the crank and do tasks all night; it works really well for that. But really only works for repetitive tasks. Like writing (Jack Kerouac wrote "On the Road" in one sitting basically, cranked out on Benzedrex), problem sets, or driving (there's a reason truckers do meth). My friend had the best description of its mode of action: It make the spreadsheet you're working on the best thing ever, you don't need the SQUIRREL outside your window to entertain you.
It's utility in studying is diminished for those without ADHD. From experience, I would caution against it; it probably will not help you. It really doesn't let you memorize more than you are capable of. It's utility in papers and projects cannot be stated enough. It helped me plow through hundreds of pages of graduate readings, and write excellent essays when I would otherwise have gotten sidetracked on topics. I've watched my cracked out English major friend (/fiend. Missing the "r" isn't incorrect. But really bad ADHD too) read a book and do a paper in one 20 hour sitting, then do another one after it.
