# Association between screen time and non-suicidal self-injury among adolescents: a compositional isotemporal substitution analysis

## TL;DR

More screen time is linked to higher risk of self-harm in teens, while more sleep and light activity lower the risk.

## Contribution

This study uses a novel statistical model to analyze how replacing screen time with other activities affects self-harm risk in adolescents.

## Key findings

- Higher screen time and sedentary time are associated with increased risk of non-suicidal self-injury.
- Replacing screen time with light physical activity or sleep reduces the risk of self-harm.
- Light physical activity and sleep time are linked to lower risk of non-suicidal self-injury.

## Abstract

In recent years, the global incidence of Non-Suicidal Self-Injury (NSSI) has risen, posing a significant challenge in public health. Adolescents are the main group affected.

A cross-sectional study was conducted using a self-administered questionnaire to collect data from 6,311 adolescents in Hefei, China. This study employed the Compositional Isotemporal Substitution Model (CISM, a statistical method that estimates health effects of replacing time in one behavior with another while accounting for the interdependent, compositional nature of 24-h time-use data) to examine the impact of Screen Time (ST), Non-Screen-based Sedentary Time (NSST), Physical Activity, and Sleep Time on NSSI among adolescents.

Compositional logistic regression analysis revealed that, relative to the remaining behavioral components, higher Light Physical Activity (LPA) (p = 0.016) and Sleep Time (p < 0.001) were associated with a reduced risk of NSSI, while higher ST (p < 0.001) and NSST (p < 0.001) time were associated with an increased risk of NSSI. CISM showed that replacing LPA with ST was linked to an elevated risk of NSSI, whereas substituting ST with LPA was associated with a reduced risk of the behavior.

The findings highlight those reasonably allocating adolescents’ daily activities, reducing ST, can help lower the risk of NSSI among adolescents.