Associations of excessive smartphone duration and unlock frequency with non-suicidal self-injury in college students

World J Psychiatry. 2026 Feb 19;16(2):112817. doi: 10.5498/wjp.v16.i2.112817. eCollection 2026 Feb 19.

ABSTRACT

BACKGROUND: The mental health impact of smartphone use remains incompletely understood. Although several prior studies have suggested a correlation between smartphone usage and non-suicidal self-injury (NSSI), reliance on self-reported data limits the accuracy of exposure assessment. Objective measurements are needed to elucidate this relationship better.

AIM: To examine the associations of objectively assessed smartphone duration and unlock frequency with NSSI.

METHODS: This cross-sectional study included 17851 college students from China. NSSI was assessed using the Ottawa Self-Injury Inventory, which includes ten NSSI behaviors. Smartphone duration and unlock frequency were objectively monitored through participant-submitted screenshots. Binary logistic and restricted cubic spline models were used for analyses.

RESULTS: Of 17851 participants, 460 (2.6%) exhibited NSSI in the past month. The mean (SD) weekly smartphone duration and unlock frequency were 49.1 (29.9) hours and 390.9 (278.2) times. After adjusting for sociodemographic characteristics, health-related behaviors, and negative life events, smartphone use was significantly and positively associated with NSSI. Compared to students with 0-21 hours/week of smartphone duration, those with ≥ 63 hours/week exhibited a significantly higher risk (odds ratio = 1.60; 95% confidence interval: 1.23-2.11). Similarly, compared to students with 0-50 times/week of smartphone unlock frequency, those with ≥ 400 times/week (odds ratio = 1.48; 95% confidence interval: 1.11-2.00) had significantly higher NSSI risk. Restricted cubic spline analyses confirmed a monotonic increase in NSSI risk with increasing smartphone duration (P value for non-linear = 0.971) and unlock frequency (P value for non-linear = 0.225).

CONCLUSION: Excessive smartphone duration and unlock frequency are associated with an elevated risk of NSSI among college students, underscoring the need to consider smartphone use behaviors in NSSI prevention.

PMID:41646624 | PMC:PMC12871394 | DOI:10.5498/wjp.v16.i2.112817