Objectively Measured Smartphone Use and Nonsuicidal Self-Injury Among College Students: Cross-Sectional Study

Area of Science:

• Mental Health Research
• Digital Health
• Adolescent Psychology

Background:

• The relationship between smartphone usage and mental health, specifically nonsuicidal self-injury (NSSI), is under active investigation.
• Previous studies relying on self-reported data may lack precision in measuring actual smartphone engagement.
• Objective measurement of smartphone use is crucial for accurate assessment of its impact on mental well-being.

Purpose of the Study:

• To investigate the association between objectively measured smartphone use and NSSI in a large cohort of Chinese college students.
• To determine specific thresholds of smartphone screen time and unlock frequency linked to increased NSSI risk.

Main Methods:

• A multicenter, cross-sectional study involving 16,668 college students across 6 universities in China.
• NSSI was assessed using the Ottawa Self-Injury Inventory, classifying participants who reported any instance in the past month.
• Objective smartphone usage data (screen time, unlocks) were collected via smartphone records.

Main Results:

• A total of 3.8% of participants reported NSSI.
• Significantly higher odds of NSSI were observed in students with ≥63 hours/week screen time (OR 1.63) and ≥400 unlocks/week (OR 1.53) compared to lower usage groups.
• Restricted cubic spline analyses confirmed a dose-response relationship between elevated smartphone use metrics and NSSI risk.

Conclusions:

• High levels of smartphone use (≥63 hours screen time or ≥400 unlocks weekly) are identified as significant risk factors for NSSI among college students.
• These findings underscore the importance of considering smartphone usage patterns in the development of interventions for NSSI.
• Objective measurement of digital behavior provides valuable insights into mental health risk factors.