It took Peter Borden a while to come around to modafinil. He never takes prescription drugs. He doesn't drink to excess. He's into acupuncture and alternative medicine. But he was working two jobs-by day, he does quantitative analysis and project management for a venture-capital-backed B2B start-up; by night, he's developing a proprietary high-­frequency trading system for a Wall Street start-up of his own-and what he needed was more time to work.

So a few months ago, Borden ordered a three-week supply by mail. ("It was a piece of cake," he says.) He popped his first pill-"the maximum suggested dose"-as soon as the package arrived, and within a few hours he started feeling a pleasant fuzziness. "Not fuzzy-headed," he says, "but crisp. A crisp softness to it." Soon he was experiencing a level of concentration he'd never imagined. "My senses sort of shifted to the visual, and my auditory sense went down. Sounds didn't even register. It was like walking around on a winter day when it just snowed. It was very easy to stay visually focused."

Next came a head rush. "I sensed it was blood actually moving to the optic nerve. Your eyes start to feel very sort of engorged, and your awareness comes to the front of your face, which is kind of a freaky sensation. I would describe it as being very much like Adderall, but without the speediness."

Tasks that were usually soul-crushing now had his undivided attention. He spent hours fine-tuning ad campaigns for his new business, and his output wasn't just faster and longer-it was better. "I didn't take as many breaks; I didn't get as frustrated; the stuff came out with fewer errors," he says. "I never felt, Oh, let's just get it done. I polished things." As long as he kept taking the pill, his focus never wavered. "Time took on an entirely different sort of quality." He was even happier. "There were some very potent anti-anxiety effects. Which was strange. I didn't think I was an anxious person, but I guess I was."

Modafinil, which is marketed as Provigil in the United States, was first approved by the FDA in 1998 for the treatment of narcolepsy, but since then it's become better known as a nootropic, a "smart drug," especially among entrepreneurs. More recently, it has attracted traders like Borden who don't just need a pick-me-up to get through a deadline; they need to be on, without a break, for months, even years at a time.