As populations age and health-care costs increase, there is likely to be a greater emphasis on monitoring, prevention and maintaining “wellness” in future, with patients taking a more active role—an approach sometimes called “Health 2.0”. With their sleep monitors and health dashboards, the aficionados of self-tracking may end up being seen as pioneers of this model. Mr Wolf draws an analogy with the Homebrew Computer Club, which met in Silicon Valley in the 1970s and went from a hobbyists’ group to the basis of a new industry. “We were inspired by our knowledge of this history of personal computing,” he says. “We asked ourselves what would happen if we convened advanced users of self-tracking technologies to see what we could learn from each other.” Self-tracking may look geeky now, but the same was once true of e-mail. And what geeks do today, the rest of us often end up doing tomorrow.