Modafinil is a medicine used to treat sleep disorders such as narcolepsy. Dubbed as a “smart drug,” modafinil is becoming increasingly popular among students to improve their concentration before an exam. But is it safe and does it really work? A recent review by researchers suggests modafinil does work for some people and is safe in the short term.

Dr. Ruairidh Battleday and Dr. Anna-Katharine Brem from the University of Oxford and Harvard Medical School analyzed all research papers on the cognitive effects of modafinil in healthy individuals who are not sleep deprived. Researchers note in the study that there have been “discrepancies” in the methodology of previous studies that have looked at the drug's overall effectiveness as a cognitive enhancer in healthy people.

Battleday said in a statement: “This is the first overview of modafinil's actions in non-sleep-deprived individuals since 2008, and so we were able to include a lot of recent data.”

Battleday found that the type of tests studies used to evaluate modafinil's cognitive benefits changed over time. At first people used quite basic tests to measure cognition, but moved to using more complex tests in more recent studies.  

“When these [complex tests] are used, it appears that modafinil more reliably enhances cognition: in particular 'higher' brain functions that rely on contribution from multiple simple cognitive processes,” he added.

Researchers evaluated 24 studies from January 1990 to December 2014 that looked at the cognitive benefits associated with taking modafinil. They found that while the so-called smart drug made little difference to creativity or working memory, it did improve decision-making and planning. The performance-enhancing capacity of modafinil varied depending on what task was being tested, with the cognitive-enhancing effects being most consistent with longer and more complex tasks. The findings were detailed in the journal European Neuropsychopharmacology. 

“We ended up having two main conclusions: first, that, in the face of vanishingly few side effects in these controlled environments, modafinil can be considered a cognitive enhancer; and, second that we need to figure out better ways of testing normal or even supra-normal cognition in a reliable manner. However, we would like to stress the point that with any method used to enhance cognition, ethical considerations always have to be taken into account: this is an important avenue for future work to explore,” Brem explained in a statement.

Of the studies that explored the effects of modafinil on a user’s mood and its side effects, 70% found it had minimal impact. Researchers concluded in the study that “Modafinil seems to be the first ‘smart drug’ that is reasonably safe for healthy people.”

It’s unclear why modafinil has this effect on the brain. The Guardian suggests one compelling theory: Modafinil increases blood flow to parts of the brain that are responsible for attention and learning.