This chapter discusses the status of research in this area, to acknowledge design and methodological challenges, and to bring additional focus to specific research design options now available to explore the key interactions that have been identified. Essentially, cognitive functions measured in this study were unaffected by mild dehydration; however, measures of mood and self-perception In all instances where sports drink was related to cognitive function, the effect disappeared when plasma glucose levels were entered into the model suggesting that the sports drink effects in this study were driven by carbohydrate content. The effects observed in Edmonds et al. suggest that in children, having a drink of water in the absence of intentional dehydration through exercise, heat or withholding fluids can impact cognitive function and mood. The effects of dehydration on mood and self-reported perceptions of well-being seem to be at least directionally greater than for cognitive function.