The aim of this study was to investigate sleep, television and computer habits and enjoyment and feelings of tiredness in school of school-age children and adolescents in Sweden. An instrument found to be valid and reliable here was distributed to 3,011 children aged 6, 7, 10, 14, and 16 years. Those sleeping less than the median length of time reported a significantly lower degree of enjoyment of school. Short sleep was found to be associated with having a bedroom TV, spending more than 2 hr a day at the TV or the computer, being tired in school, and having difficulties both in waking up and in sleeping. Discussing sleep and media habits with schoolchildren and their parents regarding matters of optimal sleep and of how media habits affect sleep and learning is seen to be an important task of the school health service. (Contains 3 tables and 1 figure.)