"Usually, the biggest red flag about school anxiety is school refusal or school avoidance," clinical psychologist Amy Mezulis, PhD, tells Popsugar. For example, being bullied, struggling with a particular subject, or being socially isolated may lead to anxiety, Dr. Mezulis says. Back-to-school anxiety tends to be more common in younger children, particularly those first starting school, Dr. Jenkins warns. Some general reasons for school anxiety include:Separation anxiety, or feeling anxiety from being away from a parent or caregiver. "It can be a physical box where they put things that help them with anxiety," Dr. Jenkins says.