Zack and Casey Lynch are a young couple who, in 2005, launched NeuroInsights, a company that advises investors on developments in brain-science technology. (Since then, they’ve also founded a lobbying group, the Neurotechnology Industry Organization.) Casey and Zack met as undergraduates at U.C.L.A.; she went on to get a master’s degree in neuroscience at U.C.S.F., and he became an executive at a software company. Last summer, I had coffee with them in the Noe Valley neighborhood of San Francisco, and they both spoke with casual certainty about the coming market for neuroenhancers. Zack, who has a book being published this summer, called “The Neuro Revolution,” said, “We live in an information society. What’s the next form of human society? The _neuro-_society.” In coming years, he said, scientists will understand the brain better, and we’ll have improved neuroenhancers that some people will use therapeutically, others because they are “on the borderline of needing them therapeutically,” and others purely “for competitive advantage.”

Zack explained that he didn’t really like the term “enhancement”: “We’re not talking about superhuman intelligence. No one’s saying we’re coming out with a pill that’s going to make you smarter than Einstein! . . . What we’re really talking about is enabling people.” He sketched a bell curve on the back of a napkin. “Almost every drug in development is something that will take someone who’s working at, like, forty per cent or fifty per cent, and take them up to eighty,” he said.

New psychiatric drugs have a way of creating markets for themselves. Disorders often become widely diagnosed after drugs come along that can alter a set of suboptimal behaviors. In this way, Ritalin and Adderall helped make A.D.H.D. a household name, and advertisements for antidepressants have helped define shyness as a malady. If there’s a pill that can clear up the wavering focus of sleep-deprived youth, or mitigate the tip-of-the-tongue experience of middle age, then those rather ordinary states may come to be seen as syndromes. As Casey put it, “The drugs get better, and the markets become bigger.”

“Yes,” Zack said. “We call it the lifestyle-improvement market.”

The Lynches said that Provigil was a classic example of a related phenomenon: mission creep. In 1998, Cephalon, the pharmaceutical company that manufactures it, received government approval to market the drug, but only for “excessive daytime sleepiness” due to narcolepsy; by 2004, Cephalon had obtained permission to expand the labelling, so that it included sleep apnea and “shift-work sleep disorder.” Net sales of Provigil climbed from a hundred and ninety-six million dollars in 2002 to nine hundred and eighty-eight million in 2008.

Cephalon executives have repeatedly said that they do not condone off-label use of Provigil, but in 2002 the company was reprimanded by the F.D.A. for distributing marketing materials that presented the drug as a remedy for tiredness, “decreased activity,” and other supposed ailments. And in 2008 Cephalon paid four hundred and twenty-five million dollars and pleaded guilty to a federal criminal charge relating to its promotion of off-label uses for Provigil and two other drugs. Later this year, Cephalon plans to introduce Nuvigil, a longer-lasting variant of Provigil. Candace Steele, a spokesperson, said, “We’re exploring its possibilities to treat excessive sleepiness associated with schizophrenia, bipolar depression, traumatic injury, and jet lag.” Though she emphasized that Cephalon was not developing Nuvigil as a neuroenhancer, she noted, “As part of the preparation for some of these other diseases, we’re looking to see if there’s improvement in cognition.”

Unlike many hypothetical scenarios that bioethicists worry about—human clones, “designer babies”—cognitive enhancement is already in full swing. Even if today’s smart drugs aren’t as powerful as such drugs may someday be, there are plenty of questions that need to be asked about them. How much do they actually help? Are they potentially harmful or addictive? Then, there’s the question of what we mean by “smarter.” Could enhancing one kind of thinking exact a toll on others? All these questions need proper scientific answers, but for now much of the discussion is taking place furtively, among the increasing number of Americans who are performing daily experiments on their own brains.

Paul Phillips was unusual for a professional poker player. When he joined the circuit, in the late nineties, he was already a millionaire: a twenty-something tech guy who had started off writing software, helped found an Internet portal called go2net, and cashed in at the right moment. He was cerebral and, at times, brusque. His nickname was Dot Com. On the international poker-tournament scene—where the male players tend to be either unabashedly schlumpy or sharply dressed in the manner of a Vegas hotel manager—Phillips cultivated a geeky New Wave style. He wore vintage shirts in wild geometric patterns; his hair was dyed orange or silver one week, shaved off the next. Most unusual of all, Phillips talked freely about taking prescription drugs—Adderall and, especially, Provigil—in order to play better cards.

He first took up the game in 1995, when he was in college, at U.C. San Diego. He recalled, “It was very mathematical, but you could also inject yourself into the game and manipulate the other guy with words”—more so than in a game like chess. Phillips soon felt that he had mastered the strategic aspects of poker. The key variable was execution. At tournaments, he needed to be able to stay focussed for fourteen hours at a stretch, often for several days, but he found it difficult to do so. In 2003, a doctor gave him a diagnosis of A.D.H.D., and he began taking Adderall. Within six months, he had won $1.6 million at poker events—far more than he’d won in the previous four years. Adderall not only helped him concentrate; it also helped him resist the impulse to keep playing losing hands out of boredom. In 2004, Phillips asked his doctor to give him a prescription for Provigil, which he added to his Adderall regimen. He took between two hundred and three hundred milligrams of Provigil a day, which, he felt, helped him settle into an even more serene and objective state of mindfulness; as he put it, he felt “less like a participant than an observer—and a very effective one.” Though Phillips sees neuroenhancers as essentially steroids for the brain, they haven’t yet been banned from poker competitions.

Last summer, I visited Phillips in the high-desert resort town of Bend, Oregon, where he lives with his wife, Kathleen, and their two daughters, Ivy and Ruby. Phillips, who is now thirty-six, seemed a bit out of place in Bend, where people spend a lot of time skiing and river rafting. Among the friendly, faithfully recycling locals, he was making an effort to curb his caustic side. Still, when I first sent Phillips an e-mail asking him to explain, more precisely, how Provigil affected him, he couldn’t resist a smart-ass answer: “More precisely: after a pill is consumed, tiny molecules are absorbed into the bloodstream, where they eventually cross the blood-brain barrier and influence the operation of the wetware up top.”

In person, he was more obliging. He picked me up at the Bend airport driving a black convertible BMW, and we went for coffee at a cheery café called Thump. Phillips wore shorts and flip-flops and his black T-shirt displayed an obscure programming joke. “Poker is about sitting in one place, watching your opponents for a long time, and making better observations about them than they make about you,” he said. With Provigil, he “could process all the information about what was going on at the table and do something about it.” Though there is no question that Phillips became much more successful at poker after taking neuroenhancers, I asked him if his improvement could be explained by a placebo effect, or by coincidence. He doubted it, but allowed that it could. Still, he said, “there’s a sort of clarity I get with Provigil. With Adderall, I’d characterize the effect as correction—correction of an underlying condition. Provigil feels like enhancement.” And, whereas Adderall made him “jittery,” Provigil’s effects were “completely limited to my brain.” He had “zero difficulty sleeping.”