'Smart drug' modafinil may not make you brainier

“Smart drug ‘may help improve creative problem solving’,” is the headline in The Daily Telegraph.

The media reports have been prompted by a new study on the effects of modafinil – a drug licensed to treat narcolepsy. Modafinil’s claim to fame is that it’s been touted as a so-called “smart drug” that can help brain performance, and is reportedly very popular among university students.

Researchers gave 64 healthy volunteers either modafinil or a placebo and asked them to complete a spoken language test. Contrary to the Telegraph’s headline, the people who took modafinil had slowed responses, and were no more accurate than the placebo (this claim seems based on a previous trial by one of the researchers).

The exact way modafinil promotes “wakefulness” is not fully understood. The test used in the research is only one measure of cognitive function, and modafinil may show improvements in the performance of other tests.

Modafinil is a prescription-only medicine that is licensed only for the treatment of narcolepsy. The drug is not without side effects, and has been associated with a risk of serious adverse effects, including psychiatric disorders and skin reactions.

Drug regulators say that the benefits of modafinil only outweigh the risks for the treatment of narcolepsy. Therefore, just because you can buy it online without a prescription, doesn’t mean you should.

Where did the story come from?

The study was carried out by researchers from the University of Cambridge, the University of Nottingham and Towson University. It was funded by the Wellcome Trust.

The study was published in the peer-reviewed journal PLOS One. This journal is open access, meaning that its contents can be read for free.

Despite referencing the current study, much of the media's reporting seemed to focus on the results of a study by one of the researchers published back in September 2014, perhaps because the press release for this study mentioned the results of the previous study. Interestingly, the title of this press release was “'Smart' drugs won't make smart people smarter”. To see just how far a message can be spun in the media, compare this to the Telegraph’s headline of, “Smart drug ‘may help improve creative problem solving’”. By contrast, The Times' headline was spot on.

What kind of research was this?

This was a randomised controlled trial that aimed to determine the effects of modafinil (a licensed treatment for narcolepsy) on the performance of healthy people in the Hayling Sentence Completion Test. The Hayling test involves listening to sentences with a missing word and providing either the missing word or a word unrelated to the sentence.

Narcolepsy is a rare sleep disorder where there is disturbance of the normal sleep-wake cycle and people suffer from excessive daytime sleepiness. The researchers performed this experiment because it has been suggested that modafinil might improve task performance, while slowing it – a phenomenon that has been referred to as “delay-dependent cognitive enhancement”. Modafinil is reportedly used off-label (outside of its licensed indication) by some healthy people, notably students, as a “smart drug” to try to enhance cognitive performance. One student website’s survey estimates that 20% of students may have taken modafinil, with almost half buying it online and many taking it daily.

A randomised controlled trial is the ideal way to determine the effects of modafinil.

What did the research involve?

The researchers randomised 64 healthy people to take a single oral dose of 200mg modafinil, or a placebo.

Two hours after people were given modafinil or placebo, the researchers assessed their performance on the Hayling Sentence Completion Test.

The Hayling test consisted of 30 sentences, each missing the last word, which were constructed to strongly constrain what the missing word should be.

In the first section, people were asked to listen to sentences, and were asked to provide, as quickly as possible, a word that correctly and sensibly completed the sentence.

Participants were then asked to complete sentences, as quickly as possible, with words unrelated to the meaning of the sentences in every way.

Both responses and reaction times were recorded, and the performance of people who were randomised to modafinil compared to those randomised to placebo.

What were the basic results?

People who took modafinil took significantly longer to provide a word.

There was no difference in the number of errors made on the test between people who received modafinil and people received placebo, showing that modafinil did not improve accuracy.

How did the researchers interpret the results?

The researchers concluded that in this study, “participants administered modafinil took significantly longer to perform the Hayling Sentence Completion Test across task sections than placebo-treated participants, without showing any improvement with regard to errors on the task”.


Modafinil is reported to be frequently used outside of its licensed indication (treatment of narcolepsy) to enhance cognitive performance. This study has cast doubt upon these supposed effects. In this RCT, modafinil slowed responses while having no effect on the accuracy of performance on the Hayling Sentence Completion Test.

The exact way modafinil promotes wakefulness is not fully understood. The Hayling Sentence Completion Test is only one measure of cognitive function, and it may be that modafinil has different effects on the performance of different tests. For example, modafinil has been a way to aid concentration and avoid distraction while studying. As one student website put it: “it’s a big boost to lazy people to force themselves to work”.

However, most importantly, modafinil is a prescription-only medication that is licensed only for the treatment of narcolepsy. The drug is not without side effects; it has been associated with a risk of serious adverse effects, including psychiatric disorders and skin reactions, as well as reducing the effectiveness of hormonal contraceptives.

This study has only assessed the one-off use of this drug in a relatively small sample of people. The study has not looked at safety outcomes, and we don’t know what adverse effects there might be for healthy individuals regularly taking this drug solely for the purpose of trying to enhance cognitive performance.

The European Medicines Agency has concluded that the benefits of modafinil-containing medicines continue to outweigh the risks only for the treatment of narcolepsy. This prescription drug cannot be recommended for any other use. Therefore, it would be unwise to buy modafinil (or similar products) online without a prescription from your doctor.

NHS Attribution