This paper reviews the literature on the effects of light on the development of premature infants and on the performance of health care professionals in neonatal intensive care units (Nicus). The literature supports the conclusion that low, and probably cycled, illuminances, are important to near- and long-term development of premature infants. However, the evidence supports the opposite conclusion for adults in the same hospital environment. The literature suggests that high illuminances improve task performance of adults working night shifts. Furthermore, a survey of nurses at one NICU shows that concern for infant well-being far outweighs other lighting considerations. Based on the literature reviewed and the results of the survey, this paper offers suggestions for lighting the Nicu.