Nonrestorative sleep and its associated factors in Chinese adolescents and the moderation effects of coffee or tea consumption.

Background: Nonrestorative sleep (NRS) is related to numerous adverse outcomes. There is rare evidence of its associated factors, especially in Chinese adolescents. This study aimed to explore the factors associated with NRS in Chinese adolescents and the potential moderation effects of coffee or tea consumption.

Methods: This cross-sectional study invited adolescents attending Grades 7-11 in Nanjing, China, to complete a self-administered questionnaire, including their NRS, stress, anxiety, physical symptoms, depression, sociodemographics, and lifestyles. Linear regressions were applied to investigate the associated factors of their NRS, with the moderation effects of coffee or tea consumption and other characteristics being tested by additionally including their interactions.

Results: Totally 481 adolescents (49% male, age 15.5 ± 1.5 years) were enrolled, with the average global NRS score of 42.16 ± 7.57. Higher family income (β = 2.01, P = 0.007), longer sleep duration (β = 2.33, P = 0.011), and moderate after-class activity (β = 1.50, P = 0.044) contributed less NRS, while higher educational level (β = -2.60, P = 0.033), more coffee or tea consumption (β = -1.68, P = 0.013), physical symptoms (β = -3.85, P < 0.001), stress (β = -0.23, P = 0.005), anxiety (β = -1.54, P = 0.045), and depression (β = -0.13, P = 0.014) contributed more NRS. Females (β = 0.82, P = 0.005), older age (β = -0.46, P = 0.029), and higher education level (β = -1.68, P < 0.001) contributed less refreshment from sleep, more physical/medical symptoms of NRS, and less daytime function, respectively. Coffee or tea consumption moderated the associations of somatic symptoms (β = 0.25, P = 0.021), stress (β = 0.29, P = 0.022), anxiety (β = 0.27, P = 0.005), and depression (β = 0.17, P = 0.021) with NRS.

Conclusions: Longer sleep duration, moderate after-class activity, reduced coffee or tea consumption, and promotion of physical and mental health may help reduce adolescents' NRS. Coffee or tea consumption may help buffer the negative associations of somatic symptoms, stress, anxiety, and depression with NRS.