In the July 1, 2006, issue of the Journal, Lauderdale et al. (1) make an important contribution to a small, but growing literature on the social determinants of sleep (2–4). They analyze and present the objectively measured sleep characteristics of early-middle-aged adults in the CARDIA study in a clear and compelling manner. Specifically, they find that Black men and women spend less time in bed, get less overall sleep, sleep less efficiently, and have higher sleep latency than their White counterparts. Near the end of their article, they suggest that “sleep may prove to play a role in the associations between socioeconomic status, race, and health” (1, p. 15). This suggestion implies that short (and inefficient) sleep patterns by Blacks compared with Whites may explain part of the health inequalities widely observed between the two groups. At face value, this hypothesis is appealing because of the intuition that short sleep is bad for one's health.