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

Abstract BackgroundThe impact of smartphone use on mental health is being rigorously debated. Some questionnaire-based research suggests that smartphone use correlates with nonsuicidal self-injury (NSSI). Self-reported data seem unlikely to capture actual smartphone use precis...

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Main Authors: Wenhua Wang, Mingyang Wu, Xiaoxiao Yuan, Xue Wang, Le Ma, Lu Li, Lei Zhang
Format: Article
Language:English
Published: JMIR Publications 2025-07-01
Series:JMIR Mental Health
Online Access:https://mental.jmir.org/2025/1/e71264
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author Wenhua Wang
Mingyang Wu
Xiaoxiao Yuan
Xue Wang
Le Ma
Lu Li
Lei Zhang
author_facet Wenhua Wang
Mingyang Wu
Xiaoxiao Yuan
Xue Wang
Le Ma
Lu Li
Lei Zhang
author_sort Wenhua Wang
collection DOAJ
description Abstract BackgroundThe impact of smartphone use on mental health is being rigorously debated. Some questionnaire-based research suggests that smartphone use correlates with nonsuicidal self-injury (NSSI). Self-reported data seem unlikely to capture actual smartphone use precisely, requiring objective measures to advance this field. ObjectiveThe aim of the study is to examine whether objectively measured smartphone use was associated with NSSI among college students. MethodsThis multicenter cross-sectional study was conducted from 2022 to 2024, enrolling college students from 559 classes across 6 universities in China. NSSI was measured by the Ottawa Self-Injury Inventory including 10 items of NSSI without suicidal intent within the past month. Participants answering “ever” were classified as having NSSI. Objectively measured smartphone screen time and number of smartphone unlocks were obtained from screenshots of smartphone use records. The association between objectively measured smartphone use and NSSI was analyzed using binary logistic regression models and restricted cubic spline regression. ResultsOf 16,668 included participants, 627 (3.8%) reported NSSI. Mean (SD) smartphone screen time and number of smartphone unlocks were 48.8 (28.8) hours per week and 271.6 (291.0) times per week. The models adjusted for different factors showed a significant association between smartphone use and NSSI. Compared to participants with 0-21 hours per week of smartphone screen time, those with ≥63 hours per week of smartphone screen time had higher odds of NSSI (odds ratio [OR] 1.63, 95% CI 1.32‐2.01). Likewise, compared to participants with 0-50 times per week of smartphone unlocks, those with ≥400 times per week of smartphone unlocks had higher odds of NSSI (OR 1.53, 95% CI 1.25‐1.88). No significant NSSI risk increase was observed for participants with 21-42 and 42-63 hours per week of smartphone screen time nor for those with 50-150 and 150-400 times per week of smartphone unlocks. Moreover, restricted cubic spline analyses showed that the increasing risk of NSSI was associated with elevated smartphone screen time and number of smartphone unlocks. ConclusionsThese findings emphasize that ≥63 hours per week of smartphone screen time and ≥400 times per week of smartphone unlocks are risk factors for NSSI among college students, and interventions targeting NSSI should consider the apparent association with smartphone use.
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spelling doaj-art-8d9dbfaae56d4a3f8cfab1f7d8c9e5b92025-08-20T03:44:54ZengJMIR PublicationsJMIR Mental Health2368-79592025-07-0112e71264e7126410.2196/71264Objectively Measured Smartphone Use and Nonsuicidal Self-Injury Among College Students: Cross-Sectional StudyWenhua Wanghttp://orcid.org/0009-0000-2934-493XMingyang Wuhttp://orcid.org/0000-0003-3001-1897Xiaoxiao Yuanhttp://orcid.org/0009-0006-6756-4320Xue Wanghttp://orcid.org/0009-0007-6113-380XLe Mahttp://orcid.org/0000-0001-7592-9779Lu Lihttp://orcid.org/0009-0009-2873-9521Lei Zhanghttp://orcid.org/0009-0000-9916-9348 Abstract BackgroundThe impact of smartphone use on mental health is being rigorously debated. Some questionnaire-based research suggests that smartphone use correlates with nonsuicidal self-injury (NSSI). Self-reported data seem unlikely to capture actual smartphone use precisely, requiring objective measures to advance this field. ObjectiveThe aim of the study is to examine whether objectively measured smartphone use was associated with NSSI among college students. MethodsThis multicenter cross-sectional study was conducted from 2022 to 2024, enrolling college students from 559 classes across 6 universities in China. NSSI was measured by the Ottawa Self-Injury Inventory including 10 items of NSSI without suicidal intent within the past month. Participants answering “ever” were classified as having NSSI. Objectively measured smartphone screen time and number of smartphone unlocks were obtained from screenshots of smartphone use records. The association between objectively measured smartphone use and NSSI was analyzed using binary logistic regression models and restricted cubic spline regression. ResultsOf 16,668 included participants, 627 (3.8%) reported NSSI. Mean (SD) smartphone screen time and number of smartphone unlocks were 48.8 (28.8) hours per week and 271.6 (291.0) times per week. The models adjusted for different factors showed a significant association between smartphone use and NSSI. Compared to participants with 0-21 hours per week of smartphone screen time, those with ≥63 hours per week of smartphone screen time had higher odds of NSSI (odds ratio [OR] 1.63, 95% CI 1.32‐2.01). Likewise, compared to participants with 0-50 times per week of smartphone unlocks, those with ≥400 times per week of smartphone unlocks had higher odds of NSSI (OR 1.53, 95% CI 1.25‐1.88). No significant NSSI risk increase was observed for participants with 21-42 and 42-63 hours per week of smartphone screen time nor for those with 50-150 and 150-400 times per week of smartphone unlocks. Moreover, restricted cubic spline analyses showed that the increasing risk of NSSI was associated with elevated smartphone screen time and number of smartphone unlocks. ConclusionsThese findings emphasize that ≥63 hours per week of smartphone screen time and ≥400 times per week of smartphone unlocks are risk factors for NSSI among college students, and interventions targeting NSSI should consider the apparent association with smartphone use.https://mental.jmir.org/2025/1/e71264
spellingShingle Wenhua Wang
Mingyang Wu
Xiaoxiao Yuan
Xue Wang
Le Ma
Lu Li
Lei Zhang
Objectively Measured Smartphone Use and Nonsuicidal Self-Injury Among College Students: Cross-Sectional Study
JMIR Mental Health
title Objectively Measured Smartphone Use and Nonsuicidal Self-Injury Among College Students: Cross-Sectional Study
title_full Objectively Measured Smartphone Use and Nonsuicidal Self-Injury Among College Students: Cross-Sectional Study
title_fullStr Objectively Measured Smartphone Use and Nonsuicidal Self-Injury Among College Students: Cross-Sectional Study
title_full_unstemmed Objectively Measured Smartphone Use and Nonsuicidal Self-Injury Among College Students: Cross-Sectional Study
title_short Objectively Measured Smartphone Use and Nonsuicidal Self-Injury Among College Students: Cross-Sectional Study
title_sort objectively measured smartphone use and nonsuicidal self injury among college students cross sectional study
url https://mental.jmir.org/2025/1/e71264
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