The potential effects of breakfast on performance and wellbeing continue to attract much interest, not least from industry, especially concerning the performance of schoolchildren. Pollitt and colleagues have argued that children are likely to be more susceptible than adults to the effects of fasting, owing to their greater brain metabolic demands relative to their glycogenic and gluconeogenic capacity. The numerous studies in this area have produced inconsistent results, which is partly attributable to variation in the populations studied, their nutritional status, and the designs used. There is a consensus that breakfast is more likely than not to benefit schoolchildren's performance, particularly if the children are already nutritionally vulnerable and have mental abilities with room for improvement. In all of us, there is a tendency for levels of arousal and alertness to rise during the morning, reaching a peak near midday. Some evidence suggests that breakfast may help to control this arousal, so that attention can be successfully focused on the task in hand. Conversely, omitting breakfast may increase autonomic reactivity, leading to less focused attention. This effect could explain the finding that children without breakfast showed better recall of objects to which they had not been asked to attend; such attention to irrelevant stimuli is also known to occur with increased anxiety. Furthermore, increasing hunger is likely to be distracting. Less attention has been paid to the effects of breakfast in adults. However, there are several studies of the effects of giving breakfast to students that show a benefit in spatial and verbal- recall tasks 1'2 h later, compared with missing breakfast. Interestingly, attention based and reaction time tasks were not improved by breakfast, and a logical reasoning task was even slightly impaired. Perhaps performance in those tests benefits more from mild arousal, which could be acutely reduced by some breakfasts. These studies did not determine whether performance later in the morning is affected by breakfast. Differential effects of breakfast content and size will be discussed below.