Introduction

To the Editor,

We sincerely thank the author for the constructive comments¹ on our article titled “Association of problematic internet use with health-related daily habits in adolescents: evidence from a school-based survey”.² We believe that the presented criticisms will shed light on future studies on similar topics.

The author emphasizes the importance of assessing not only the duration of use but also the reason adolescents use the internet and the activities they engage in. The specific purpose of focusing on internet usage duration in the current study was that we anticipated increased usage duration as the primary problem. Considering this shortcoming of our study, we emphasized the importance of examining variables such as adolescents’ internet use purposes, motivations, and which devices they prefer in the limitations section. Although a recent study found that those who primarily spent time on social media or games reported significantly higher levels of problematic internet use compared to their peers who used the internet primarily for academic purposes³, cohort studies are needed to establish a causal relationship between problematic internet use (PIU) and both usage duration and content.

We find the author’s recommendation to use standardized measurement tools to assess daily health habits warranted. We previously discussed this issue in the limitations section of our study. In the current study, sleep problems were assessed with symptom-based items; however, future research could obtain more precise and standardized data by employing validated instruments such as the Pittsburgh Sleep Quality Index (PSQI).⁴

Furthermore, it is plausible to speculate that PIU and other health behaviors may arise from the disruption of common underlying mechanisms, such as impaired self-regulation or circadian misalignment. Our findings support the idea that PIU often co-occurs with multiple lifestyle disorders rather than existing alone. We also agree with the author regarding the limitations of our study’s cross-sectional nature regarding causation. While our study findings suggest an association between PIU and health-related daily habits, causality cannot be inferred. Longitudinal studies are needed to clarify these bidirectional relationships, such as whether PIU triggers these negative habits or whether the presence of these habits leads to PIU.

We appreciate both the author’s methodological considerations and insightful suggestions for future research. A detailed evaluation of internet and other digital addictions, not only in terms of duration but also in terms of content, and examining health-related variables with validated measurement tools, will contribute to a more comprehensive understanding of PIU among adolescents.

Source of funding

The authors declare the study received no funding.

Conflict of interest

The authors declare that there is no conflict of interest.