David Berry is sitting in a midtown Manhattan coffee shop, taking a break from a carbon-trading conference across the street, when a news report on the wall-mounted television catches his eye. The CNN dispatch describes how scientists have shown, in animal experiments, that Viagra might be used to alleviate symptoms of jet lag.

"It's interesting," Berry says, chuckling, as his eyes wander back to the screen. "We were talking about a year ago of using Viagra to treat jet lag." One side effect of Viagra widely reported in the medical literature has been the perception of blue light, he continues, and blue light has also been shown to reset circadian clocks in humans. "I like when I see these things actually come true," he says.