But does modafinil make you smarter?
A number of small studies over the years have looked at the cognitive effects of modafinil in healthy people. These studies tend to be limited by their size and the variety and methods of tests used to measure the effects. But a systematic review of the available data, conducted by Oxford University in 2015, suggested that modafinil does have a positive effect on concentration when carrying out specific tasksiii (REF). They also reported a relatively low level of people suffering side effects. These results led to a number of media reports hailing the advent of the first ever 'safe, effective smart drug'.
Conversely, a randomised, double-blind trial published in 2014 provides some evidence that modafinil may actually impair cognitive ability [iv], at least in one specific type of test. The results showed that people given a single dose of modafinil had a reduced response time compared to placebo, but without improving the accuracy of their responses.
Bearing in mind the studies in question involved a small number of doses taken for a short period, the risks of longer term use or higher doses would be difficult to identify and there is no evidence that any benefits would continue after the first few uses.
The jury is still out on whether modafinil really does improve mental performance.