Many people are familiar with melatonin, a hormone that helps ready the body for sleep. But there's another, lesser-known chemical in the brain, called orexin, that tips the scale in the other direction: waking the body up. In 1999, two scientists independently uncovered the function of orexin and published papers about it. Dr. Masashi Yanagisawa, a molecular biologist and physician now at the University of Tsukuba in Japan, came across orexin while studying the interaction of receptors and chemicals in the brain. Dr. Emmanuel Mignot, now the director of the Stanford Center for Narcolepsy, homed in on orexin while studying narcoleptic dogs. (His Chihuahua, named Watson, has narcolepsy, and h...