Association of Nighttime Sleep Duration with Depressive Symptoms and Its Interaction with Regular Physical Activity among Chinese Adolescent Girls

Depression has become a major mental health concern among adolescents globally, and the relationship between depressive symptoms and nighttime sleep duration among adolescent girls remains unclear. This study aimed to examine the association between nighttime sleep duration and depressive symptoms among Chinese adolescent girls. This cross-sectional study, conducted in 2018, included 4952 girls aged 10–19 years from the eastern, central, and western regions of China. Depressive symptoms were assessed by the Patient Health Questionnaire-9, and categorized into depressive symptoms and non-depressive symptoms. Logistic regression models were used to estimate the odds ratios (ORs) of depressive symptoms. After adjustment for covariates, adolescent girls with a nighttime sleep duration of <7 h/night (OR = 2.28, 95% CI: 1.76–2.95) and 7 h/night (OR = 1.82, 95% CI: 1.48–2.24) were associated with increased risk of depressive symptoms, compared to those with a sleep duration of 8 h/night. An interaction between nighttime sleep duration and regular physical activity on the risk of depressive symptoms was observed (p for interaction = 0.036). Among both girls with and without regular physical activity, a sleep duration of <7 h/night was associated with increased odds of depressive symptoms, and the magnitude of the ORs among girls with regular physical activity was lower than those without regular physical activity. This study found a significant association of short nighttime sleep duration with increased risk of depressive symptoms, and demonstrates the importance of maintaining adequate nighttime sleep duration and ensuring regular physical activity in improving depressive symptoms among adolescent girls.