Is it cheating?
So despite the risks of side effects and dangers of buying it illegally, the pressure to perform is just too great and you decide to start using modafinil.
Will anything you now achieve be on the basis of your own merits or will it be due to the drug you have taken? You might be able to justify it to yourself; it's just like drinking coffee isn't it? But what do the universities say? Is it cheating? Could you be disqualified from your degree? Perhaps more importantly, what would your friends and classmates say? Would they think it fair? Would they see you as a cheat? Is it worth risking your degree and your friendships to gain an edge?
You are an intelligent person; you've made it through the school system, passed your exams and got in to university by your own merits. Don't spoil it now; deep down you'll always wonder if you would have been good enough without the drug, there will always be a question mark over your performance. There is just no substitute for hard work and effort, to give you that sense of personal achievement.
If you are worried about exam performance, or suffering stress because of exams, speak to your tutor in the first instance. They can guide you through good revision techniques and identify areas where you can improve your performance. Working together in revision groups can help focus the mind on priorities and allows the sharing of ideas and insights. Talking to friends and family can also help you manage stress and anxiety and put things into perspective.
References and sources:
[i] BBC News, 11th February 2016; Rise in 'smart drug' use at Bristol University; http://www.bbc.co.uk/news/uk-england-bristol-35541107
[ii] The Pharmaceutical Journal, 19th February 2013; What is the situation with "smart drugs" use among UK university students? http://www.pharmaceutical-journal.com/news-and-analysis/news/what-is-the-situation-with-smart-drugs-use-among-uk-university-students/11117393.article
[iii] Battleday RM, Brem AK; Modafinil for cognitive neuroenhancement in healthy non-sleep-deprived subjects: A systematic review; European Neuropsychopharmacology, November 2015Volume 25, Issue 11, Pages 1865-1881, accessed online at http://www.europeanneuropsychopharmacology.com/article/S0924-977X(15)00249-7/fulltext
[iv] Mohamed AD, Roberts Lewis C; Modafinil Increases the Latency of Response in the Hayling Sentence Completion Test in Healthy Volunteers: A Randomised Controlled Trial; Journal Plos One, November 12, 2014, accessed online at http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0110639