Moderate levels of anxiety could help teenagers to succeed at school, according to research.
A study suggests there is a link between having some worries and the chances of completing school.
But pupils with high or low levels of anxiety are more likely to leave secondary education without a qualification.
The paper, which is based on data from around 4,900 Canadian students in Quebec, examines the links between symptoms of depression and anxiety and completing school.
Students who took part were asked to complete questionnaires on how they felt in the previous week, and this information was combined with official data on school non-completion rates in Quebec.
The findings showed an association between anxious symptoms and school non-completion, the study says, "with both low and high levels of anxiety associated with increased risk of students leaving secondary school without qualification".
It adds that this association also "suggests that students may be at optimal disposition to succeed in school when they experience moderate levels of anxiety in general, and not just in relation to specific tasks."