Characterization of Smartphone-related Diseases Using the Phonix Care Application (PHX_2022_1)

Characterization of Smartphone User Profiles (Caractérisation de Profils d'Utilisateurs de Smartphone)

The goal of this observational study is to describe how adolescents and young adults use screens in their daily lives and to identify different profiles of screen use ranging from low to excessive. The study also aims to understand how screen-use behaviors relate to health, motivation, and sociodemographic factors.

The main questions it aims to answer are:

What are the objective and self-reported patterns of screen use (e.g., frequency of use, types of apps, daily time spent, usage periods)?

Do distinct screen-use profiles emerge (low, moderate, intensive/excessive) when taking into account:

Age, gender, educational track (general, technological, vocational), Parents' socioeconomic status, Health variables (sleep quality, physical activity/sedentary behavior, well-being), Cognitive and conative variables (self-regulation capacity, academic motivation)? Are excessive users characterized by specific patterns, such as intensive use of social media, video platforms, or video games combined with mood problems, sleep difficulties, or motivational issues? Do screen-use profiles vary depending on age group (middle school, high school, university) and gender?

Are there mediating mechanisms explaining excessive use? Specifically:

Does poor self-regulation mediate the link between screen-use intensity and well-being? Do sleep problems mediate the link between excessive nighttime use and mood disturbances (anxiety, depression)? Do academic motivation and cognitive factors mediate differences between moderate and excessive users? If groups differ, researchers will compare low-use, moderate-use, and excessive-use profiles to determine whether they show meaningful differences in health, motivation, and sociodemographic characteristics.

Participants will:

Install a smartphone application that passively records daily screen-use indicators (e.g., usage time, app categories, frequency of openings, time windows of use).

Complete questionnaires assessing:

Self-reported screen use, Sleep, physical activity, well-being, Mood variables (anxiety, depression), Self-regulation, Academic motivation, Sociodemographic factors (age, gender, parents' SES, educational track).

Study Overview

• Status: Completed
• Conditions: Screen Time
• Intervention / Treatment: Device: PhonixDiag Smartphone Monitoring Tool

• Study Type: Observational
• Enrollment (Actual): 171

Contacts and Locations

Study Locations

• France
  • Saint-Martin-d'Hères, France
    • Université Grenoble Alpes

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

Participants were recruited from secondary schools and universities in Grenoble, France, through institutional communication channels and digital platforms. Recruitment occurred within educational settings located in various regions, allowing inclusion of adolescents and young adults enrolled in middle school, high school, or university programs.

Description

Inclusion Criteria:

• Own an Android smartphone
• Have at least 200 MB of storage on your smartphone
• Be in middle school, high school, or university
• Be enrolled in a school within the Grenoble academy district

Exclusion Criteria:

• Own an iPhone
• Participate in an interventional study in the field within the last six months
• Not sign the consent form

Study Plan

How is the study designed?

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Objective Screen Use Time (Daily Median Over Monitoring Period)	Objective screen-use time will be measured using the PhonixDiag smartphone monitoring tool. The outcome corresponds to the median daily duration (in minutes) spent on smartphone applications across the full monitoring period. This includes all app categories and reflects real-world behavioral engagement with digital media. The measure will be used to classify participants into usage profiles (low, moderate, excessive) and to examine associations with age, gender, socioeconomic status, sleep, physical activity, well-being, self-regulation, and academic motivation.	From enrollment to the end of treatment at 4 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Self-Reported Screen Use (Questionnaire Score)	Participants will self-report their perceived daily screen time and frequency of use across app categories. Questionnaire responses will be used to compare subjective and objective measures of screen use and to explore potential biases in self-estimation.	1 day
Sleep Quality (Self-Reported Index)	Participants will complete a self-reported measure of sleep quality, including sleep duration, bedtime regularity, and perceived sleep disturbances. This outcome will be explored in relation to objective nighttime digital activity and mood variables.	7 days
Physical Activity and Sedentary Behavior (Self-Reported Levels)	Participants will report their weekly physical activity, sitting time, and sedentary behaviors using standardized self-report questionnaires. These variables will be examined as predictors or correlates of screen-use profiles.	7 days
Well-Being (Self-Reported Score)	Participants will complete a validated well-being questionnaire assessing positive mental health, life satisfaction, and emotional balance. Scores will be compared across screen-use profiles and related to objective digital behaviors.	1 day
Anxiety (Self-Reported Symptom Score)	Anxiety symptoms will be assessed using a standard validated questionnaire. This outcome will be used to examine associations with objective digital behaviors.	1 day
Depressive Symptoms (Self-Reported Score)	Participants will complete a validated depression questionnaire. Scores will be examined in relation to objective smartphone use indicators and will support analyses of risk factors for problematic digital use.	1 day
Self-Regulation Capacity (Self-Reported Score)	Self-regulation will be assessed using a validated questionnaire measuring planning, inhibition, and control. This measure will help characterize screen-use profiles and explore cognitive factors associated with excessive use.	1 day
Academic Motivation (Self-Reported Score)	Participants will complete a validated measure of academic motivation covering intrinsic, identified, introjected, and external regulation. Motivation scores will be analyzed across usage profiles to investigate potential conative differences between groups.	1 day

Collaborators and Investigators

• Sponsor: Phonix Health

Study record dates

Study Major Dates

• Study Start (Actual): April 1, 2022
• Primary Completion (Actual): March 1, 2023
• Study Completion (Actual): March 1, 2023

Study Registration Dates

• First Submitted: December 6, 2025
• First Submitted That Met QC Criteria: December 6, 2025
• First Posted (Actual): December 19, 2025

Study Record Updates

• Last Update Posted (Actual): December 19, 2025
• Last Update Submitted That Met QC Criteria: December 6, 2025
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Keywords: depression; adolescent; young adult; smartphone; academic motivation; digital phenotyping; problematic digital use
• Additional Relevant MeSH Terms: Behavioral Symptoms; Behavior; Depression
• Other Study ID Numbers: PHX_OBS_CERGA_2022

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No