Sleepiness is more complicated than we might think. If we don't sleep as well or for as long as we believe we should, the idea of sleepiness lingers, and we might feel its effects more than we should. In addition, if we believe we aren't sleeping well, we are likely to worry about it and sleep worse. Dr Leon Lack is director of the sleep research laboratory at Flinders University in South Australia and is, with his team, developin...