Smartphone use, sleep, and mental health in Korean adolescents.

Prolonged smartphone use was associated with higher odds of low sleep satisfaction in Korean adolescents.

• Cross-sectional analysis of 51,718 Korean adolescents using nationally representative data
• Prolonged smartphone use defined as ≥420 min/d compared to <180 min/d
• OR for low sleep satisfaction: 1.22 (95% CI: 1.14, 1.30)
• Multivariable logistic regression accounted for complex survey sampling and adjusted for potential confounders

Prolonged smartphone use was associated with higher odds of generalized anxiety disorder (GAD) in Korean adolescents.

• Comparison group: ≥420 min/d vs. <180 min/d
• OR for GAD: 1.27 (95% CI: 1.15, 1.41)
• Association persisted after additional adjustment for sleep satisfaction
• Association persisted after excluding participants at high risk of smartphone overdependency

Prolonged smartphone use was associated with higher odds of depressive symptoms in Korean adolescents.

• Comparison group: ≥420 min/d vs. <180 min/d
• OR for depressive symptoms: 1.42 (95% CI: 1.32, 1.52)
• Association remained after additional adjustment for sleep satisfaction
• Association remained after excluding participants at high risk of smartphone overdependency

Prolonged smartphone use was associated with higher odds of suicidal ideation in Korean adolescents.

• Comparison group: ≥420 min/d vs. <180 min/d
• OR for suicidal ideation: 1.36 (95% CI: 1.25, 1.48)
• Association persisted after additional adjustment for sleep satisfaction
• Association persisted after excluding participants at high risk of smartphone overdependency

Prolonged smartphone use was associated with higher odds of suicidal attempts in Korean adolescents.

• Comparison group: ≥420 min/d vs. <180 min/d
• OR for suicidal attempts: 1.70 (95% CI: 1.43, 2.02), the highest OR among all mental health outcomes examined
• Association persisted after additional adjustment for sleep satisfaction
• Association persisted after excluding participants at high risk of smartphone overdependency

The associations between prolonged smartphone use and poor mental health outcomes were independent of sleep satisfaction.

• Positive associations with GAD, depressive symptoms, suicidal ideation, and suicidal attempts persisted after additional adjustment for sleep satisfaction
• This suggests smartphone use duration affects mental health through pathways beyond sleep disruption alone
• Study used cross-sectional design, limiting causal inference

The associations between prolonged smartphone use and poor mental health persisted even among adolescents without problematic smartphone use.

• Analyses were repeated after excluding participants at high risk of smartphone overdependency
• Positive associations with all four mental health outcomes remained significant after this exclusion
• Suggests that moderate smartphone use without addiction may still be associated with poor mental health