A medication called modafinil is commonly used to treat people who experience narcolepsy, but it's suspected that the vast majority of those who use the drug are taking it for another purpose that isn't medically authorised: as a general cognitive enhancer for tasks such as studying or meeting a deadline.

Now a comprehensive review of the medication has looked at this 'off licence' use of the drug by healthy, non-sleep-deprived subjects to determine whether modafinil is safe – and to confirm whether the belief that it acts as a general-purpose 'smart drug' is grounded in reality.

According to researchers from the University of Oxford in the UK and Harvard Medical School in the US, modafinil delivers on both counts, constituting what's thought to be the first safe smart drug that can provide demonstrable cognitive and concentration benefits. Brainpower in a pill, in other words.

The team evaluated all the research literature on modafinil's cognitive enhancement effects, looking at 24 papers that studied the medication's impact on tasks such us planning, decision making, memory, learning, and creativity. Their findings, published in European Neuropsychopharmacology, showed that modafinil does indeed confer cognitive benefits, although these differ depending on the task at hand.

According to the study, modafinil doesn't improve our working memory or flexibility of thought, but it does benefit our capacity to make decisions and plan - "'higher' brain functions that rely on contribution from multiple simple cognitive processes," said co-author Ruairidh McLennan Battleday in a press release.

Promisingly, the medication also showed little in the way of side effects, with 70 percent of studies looking at mood or side effects indicating very little overall effect. "[I]n the face of vanishingly few side effects in these controlled environments, modafinil can be considered a cognitive enhancer," said Anna-Katharine Brem, co-author.

The finding that modafinil amounts to the first real example of a 'smart drug' that can improve people's higher brain functions is bound to create controversy. While the mind-altering medication isn't prescribed for any such general use – which is unlikely to change in the near future – the very fact that a scientifically verified brainpower enhancer exists poses some interesting questions.

According to Guy Goodwin, president of the European College of Neuropsychopharmacology, who was not involved with the research: "Previous ethical discussion of such agents has tended to assume extravagant effects before it was clear that there were any. If correct, the present update means the ethical debate is real: how should we classify, condone or condemn a drug that improves human performance in the absence of pre-existing cognitive impairment?"