Modafinil

Modafinil, a drug licensed for sleep disorders, is also widely used as a study drug or cognitive enhancer, but the evidence for its effectiveness in this domain is scant.

Sold under the brand name Provigil among many others, modafinil promotes wakefulness, and is taken by people with narcolepsy to stop them feeling sleepy. Since the drug was developed in the 1980s, the armed forces of several countries have been interested in using it to help soldiers and pilots work for long periods without sleep, but much of this research has been done in secret.

Some doctors use modafinil while working without sleep, but whether this helps them is unclear. In one small study, doctors who took modafinil after a sleepless night did better on cognitive tests than those given a placebo, but there was no difference in their motor skills on a surgical training simulator.

How the drug works isn’t well understood. Like other stimulants, it stops nerve cells from reabsorbing dopamine, an excitatory chemical, after it is released into synapses. But unlike other stimulants, it isn’t associated with addictive highs and painful lows. People who use it to stay awake don’t seem to need more sleep to catch up later.

Staying awake is one thing, but can it actually make you smarter? The research on this question is inconsistent, but a review found that the drug does appear to improve attention, learning and executive function, especially in more complex tests. Another meta-analysis found a small positive effect on cognitive functioning, and concluded that modafinil has limited potential to act as a cognitive enhancer.

For most people, modafinil appears to be safe, but some serious side effects have been reported, including skin rashes and symptoms of psychosis.