Figure 1.

Relationship between sleep duration on school nights and odds ratio for depression/anxiety (General Health Questionnaire-12 score ≥ 4) by sex and school grade (i.e., grades 7–9 and 10–12). Odds of having depression/anxiety compared with the reference group (those who sleep 8.5–9.5 h in males and 7.5–8.5 h in females), adjusting for bedtime regularity and grades. Odds ratios and their 95% confidence intervals are indicated by circles and bars, respectively. *P < 0.05, **P < 0.01, ***P < 0.001.