Modafinil (Wikipedia link) is a drug approved in many countries for specific medical conditions such as narcolepsy. We don't, however, have a good idea how it works.
But is is one of several drugs (including the unrelated stimulant Ritalin, which is approved for use in ADHD) which are believed by many to be cognitive enhancers. According to a BBC story:
It has been used by the military to keep soldiers awake in times of combat and its use is thought to be on the rise among shift workers, such as nurses, doctors, and pilots. Modafinil is also said to be popular among jet-lagged academics...
...A survey of 1,400 adults carried out by Nature found that one in five said they had taken Ritalin, Provigil (modafinil) or beta-blockers to stimulate focus, concentration, or memory - not for any medical condition.
A more recent BBC story on the ethical issues raised by the possibility of cognitive enhancers also highlights how significant their use is thought to be:
Several surveys reveal that many students now use brain-enhancing “smart” pills to help boost their exam grades, which raises the question about whether colleges and universities should insist candidates are “clean” in the same way that Olympic athletes have to prove they are drug-free to compete... ...Dr Robin Lovell-Badge, of the Medical Research Council and who chaired one of the workshop sessions that formulated the report, said: "It was clear from discussions that cognitive-enhancing drugs present the greatest immediate challenge for regulators and other policymakers.
"They are simple to take, already available without prescription, and are increasingly being used by healthy individuals."
So Modafinil is clearly being used off label and people believe its use improves their performance. But is there clear evidence that it improves intellectual performance? In simpler language, does Modafinil make you smarter?