This exploratory comparative survey of the ecology of human sleep arises from a question posed by a pediatrician who studies mood disorders and sleep (Dahl, 1996; Dahl et al., 1996). In an attempt to gain insights into sleep regulation from ecological theory and research, he questioned what anthropologists know about sleep. The bald, if somewhat overstated, answer was: zero. Sleep, in its ubiquity, seeming nonsociality, apparent universality, and presumed biologically driven uniformity, has been overlooked as a background variable. Amazingly, it has not engaged a discipline dedicated to the study of human behavior, human diversity, and their cultural biological bases. A notable exception is the evolutionary-ethologically informed approach to the anthropological study of sleep pioneered by the work of McKenna and colleagues on sleep arrangements, infant state regulation, and risk for sudden infant death syndrome or SIDS (McKenna, 1991, 1992, 1996; Mosko, McKenna, Dickel, & Hunt, 1993). Harkness and Super have also documented cultural variation in infant sleep in relation to their studies of child care practices (Harkness & Super, 1996; Super, Harkness, van Tijen, van der Vlugt, Fintelman, & Kijksta, 1996), and scattered reports document sleep behavior (Ferreira de Souza Aguiar, Pereira da Sliva, & Margues, 1991).