A large body of research links performance pay to poorer worker health. The exact mechanism generating this link remains in doubt. We examine a common suspect, that performance pay causes employees to work longer hours in pursuit of higher pay. Using representative data for the UK, we demonstrate that performance pay is associated with more work hours and a higher probability of working long hours. Yet approximately two thirds of these differences reflect worker sorting rather than behavioral change. The remaining influence appears too small to generate the differences in health except for blue-collar occupations that we isolate.