Have you ever wanted to play better chess? To think and work more effectively, seeing moves 10 steps ahead? Vanquishing opponents with mental energy to spare? Well now you can, with cognitive-enhancement drugs.

That’s how the first half of the pharmaceutical commercial might go. The small-print, fast-talking second half would say that limitations apply. Some of the drugs are addictive and likely to alter one’s sleep habits and heart rate and general sense of self. The drugs don’t work if you don’t know how to play chess.

For professional chess players, though, medicinal “neuro-enhancement” (as it’s sometimes dubiously known) could bring in somewhere between 6 and 15 percent more wins. That’s according to the first large study of “highly skilled tournament chess players” comparing their performance in states of medication and sobriety—a study that the World Chess Championship’s publication World Chess has called “landmark” and “groundbreaking.”

A collaborative experiment from researchers throughout Germany and Sweden led by psychiatrist Klaus Lieb at the University of Mainz found that two prescription medications improved chess-winning rates: modafinil (sold most commonly as Provigil) and methylphenidate (sold as Ritalin).

Both are heavily regulated in much of the world, the latter prescribed to people who carry a diagnosis of attention-deficit-hyperactivity disorder, or ADHD. Modafinil is sometimes prescribed off-label for the same reason, but its FDA-approved use is to maintain alertness (pro-vigilance) in people with narcolepsy, shift-work disorder, and sleep apnea. (Modafinil is never to be given to children, the FDA warns, lest it cause “increased suicidal thoughts,” “hostile behavior,” and/or “sudden loss of muscle tone.” The listed side effects in adults include depression, anxiety, aggression, and “other mental problems.”)

But where there is the potential for improvement, risks will and are being taken. Taking Ritalin or Provigil for purposes of hyper-performance currently constitutes illegal drug abuse, but President Donald Trump’s vision for the Food and Drug Administration includes making the marketing of drugs for “off-label” uses much easier for pharmaceutical companies. This would put onus on patients and doctors to weigh known risks and benefits against outsized marketing campaigns.

In that light, Lieb and colleagues have been questioning the role of such drugs and their use as neuro-enhancers—and whether adults who already were performing at high levels cognitively could actually go higher. For the current study, the team turned to chess pros, among the highest of high-functioning thinkers. Thirty-nine players came into the lab on sequential days and took a pill that contained a substance of a nature unknown to the them—an aforementioned drug or a placebo. They then squared off in a total of 3,059 games in various mental states against computer programs.

The results both confirmed and called to question some important emerging ideas about cognitive enhancement.

“We primarily thought that it is not possible to enhance high cognitive tasks and were astonished to find such results,” Lieb told readers of World Chess. The authors estimate that the effect was enough to propel a player up the rankings from around 5,000th in the world to closer to 3,500th. I believe when one plays chess competitively, that’s a big deal. Modafinil users saw an 8 to 15 percent increase in victories, and methylphenidate users saw 6 to 13 percent.

The researchers tested caffeine, too, and it had a strong effect—not far below that of the prescription medications. (The caffeine dose was big, though: 400 milligrams, or around four average cups of home-brewed coffee. Or one of Starbucks’ enormous venti cups.)

But how could these drugs actually make a person better at chess?

The novel finding was that the medications didn’t seem to actually make people think more quickly, exactly. Possibly even the opposite. Because while the overall result was that these drugs were associated with more winning, the users also lost more games because they ran out of time. That’s right. Time. Our old nemesis. The emptiness that consumes us all. Time.

The researchers write that their findings suggest “neuro-enhancers do not enhance the quality of thinking and decision-making per time unit,” but the drugs “can improve the players’ ability or willingness to spend more time on a decision and hence to perform more thorough calculations.”

That is, these drugs don’t make us think better, it seems, only more devoted to thinking. Lieb and colleagues attribute the performance improvement to “increased reflection time,” or the time between an opponent’s move and the player’s next move, measuring an average of 437 seconds on placebo that jumped up to around 550. On the drugs, “individuals are reflecting longer in the sense of accumulating more information,” the researchers write, “i.e., investigating more lines and making better moves on average.”

Although that meant more losses due to time, the net effect was still positive since “increased reflection times under stimulants led to a much better quality of play.” These substances alter a person’s priorities, hijacking something along the pathway between perception and reaction. The players knew the games were timed, and yet they were less impetuous with their moves—or more brazen with regard to running out of time.

If these medications fundamentally change decision-making in chess, how else do they change behavior, in individuals and throughout societies? Who among us has not tried some stimulant and become devoted to the suddenly urgent and fascinating task of organizing socks, or arranging one’s desktop, or writing elaborate emails that didn’t need to be so elaborate, or to exist at all?

A 2014 study of people trying the Stroop test (reading the names of various colors printed in fonts of dissonant colors) found that methylphenidate increased accuracy but decreased speed. Building on that idea, Lieb and colleagues propose that “stimulants may influence the speed-accuracy trade-off during cognitive tasks. In other words, these substances may be able to convert fast and shallow thinkers into deeper but somewhat slower thinkers.”

This would mean that certain drugs will be useful to certain types of thinkers doing certain types of tasks. To think of them as “doping” is to imply that they are broadly beneficial, even though encouraging reflective decision making would only enhance performance when time constraints aren’t a major factor. Still, the World Chess Federation implemented drug testing in 1999 with an optimistic eye to eventual inclusion in the Olympic games—requiring signatory to the World Anti-Doping Agency, meaning players are already prohibited from using modafinil or methylphenidate.

Apart from the moral dilemmas inherent in doing anything that might be considered “doping” by an international agency, Lieb warned the readers of World Chess, as I warn you here, that using these drugs “may cause severe side effects and dependency, especially with repeated use.” Though of course the ultimate effect of admonitions against using drugs tends to be somewhere between ineffective and counterproductive. Research like this creates tension between data that say these substances will improve me and don’t take drugs.

As cognitive-enhancement data like these come out in years ahead, the challenge will be to consider how these substances will occasionally work as tools to help people, in deliberate ways, as opposed to keeping swaths of people constantly enhanced or never enhanced. As such, the World Anti-Doping Agency is considering adding caffeine to its banned substances list—which would affect not just chess but basketball, football, and all other sports—though only at high doses or when its use violates “the spirit of the sport.” Lieb and colleagues note that the fact that the agency and the World Chess Federation “do not see any problems with caffeine ... is questioned by our data.”

A ruling is expected near the end of this year. In the meantime, caffeine remains perfectly legal in any amount and circumstance and is used in increasing quantities by almost all adult humans on a daily basis. Many are doing fine.

Though maybe they could be doing better.