Gender differences in factors associated with symptoms of depression among high school students: an examination of the direct and indirect effects of insomnia symptoms and physical activity

OBJECTIVE: Scant research exists on the gender-specific association between physical activity, insomnia symptoms and depressive symptoms among adolescents. The present study investigates the direct and indirect association of insomnia and physical activity with symptoms of depression. DESIGN: In a community-based sample (N = 1485) we investigated factors associated with symptoms of depression focusing on insomnia. The study also included measures of physical activity and controlled for parental work- and sexual minority status. Body mass Index (BMI) was calculated for a sub-sample (n = 617) reporting weight and height. RESULTS: The results showed that self-reported insomnia was highly prevalent, and the association between insomnia and depression was strong. The association between insomnia and depression was significantly stronger for girls than for boys. The effect of physical activity was substantially weaker compared to insomnia. Insomnia mediated the relationship between physical activity and depression for both boys and girls. Despite expectation based on the existing literature, BMI showed no association with symptoms of depression or physical activity. CONCLUSION: The results address the importance of a gender-specific approach when investigating mental health among adolescents. Given the high prevalence, interventions aimed at reducing insomnia is important in the prevention of mental illness, especially among girls.