The focus of this paper is the process of homeostasis by which the body seeks to regulate its internal environment. In particular, we present a global model for a set of consumer behaviors that may vary across cultures as a direct response to the intensity and duration of sunlight and experienced temperature. This process creates physical and psychological needs, so that changes in sunlight and temperature may be reflected in various behaviors. We integrate research findings from the neural sciences and psychology to generate testable predictions of relevance to the marketing literature. These hypotheses predict how the physical environment motivates variations in the consumption of different types of products, and how mood, expressed affect, and related affective behaviors may vary across cultures. We also consider how variations in sunlight and temperature may affect consumer behaviors related to consumers' optimal stimulation levels. We conclude by discussing the implications of a physiological model on the debate of global convergence in consumer behavior.