Abstract
This study assessed the contribution of lifestyle variables (diet, exercise, bed-time, television watching) to tiredness in school children. Eight hundred and sixty-five boys at a statefunded grammar school completed a questionnaire about lifestyle and perceived tiredness in five contexts (in lessons, before school, in break times, in the early evening, and at weekends). Lifestyle was more strongly associated with tiredness in lessons compared with tiredness in other contexts. In a multiple regression, tiredness in lessons was independently related to diet, age, bed-time and television watching. Diet contributed most of all measured lifestyle variables, and there were independent positive associations (snack foods) and negative associations (vegetables, fish, mashed/boiled potatoes) with tiredness in lessons. Overall, 11% of the variance of tiredness in lessons was explained by age and lifestyle, but there was evidence of a U-shaped relationship between level of food intake and tiredness in the case of some foods, and between perceived fitness and tiredness. The causal direction between lifestyle and tiredness in lessons can only be inferred from these cross-sectional data. However, it seems likely that lower consumption of healthy food, later bed-time and more television watching (in order of contribution) are causing greater tiredness in lessons. The association between snack foods and tiredness in lessons may be because the former causes the latter or vice versa.