A study published this week, however, makes bold claims on the properties of one of the most well-known smart drugs: modafinil. Modafinil is a medication prescribed for sleep conditions such as narcolepsy, but students, execs, and hacker types have documented taking the drug even when they're sleeping just fine—and getting brain enhancing effects as a result.

The new paper, published in European Neuropsychopharmacology, supports the general claims of modafinil fans. Ruairidh Battleday and Anna-Katharine Brem from the University of Oxford and Harvard Medical School reviewed studies that looked at the effect of modafinil on non-sleep-deprived people and came away stating that modafinil "may well deserve the title of the first well-validated pharmaceutical 'nootropic' agent."

What's more, they reported that they "did not observe any preponderances for side effects or mood changes." The studies they looked at reported only minor adverse effects and little effect on mood—"if anything improving it."