Digital Detox Study: A Randomized Controlled Trial
Phase: NA
Conditions: Prevention, Digital Health, Smartphone Addiction
Sponsor: Danube University Krems

 
 
 
 
page 1 of 18 
 
 
Study protocol 
Digital Detox Study 
A randomized controlled trial with two unblinded, parallel arms  
assessing the effect of reducing smartphone screen time on mental health 
 
 
Authors:  
Katja Haider, BA MSc,  
 
 
Prof. Dr. Christoph Pieh 
Version:  
01 (original protocol) 
Clinical trial phase:  
n.a. 
Release date:  
March 17, 2025 
 
 
 
 
 

Digital Detox Study 
 
 
University for Continuing Education Krems 
Study Protocol 
 
 
 
 
 
 
page 2 of 18 
Table of contents 
1. 
Introduction ................................................................................................................ 4 
1.1. 
Background ....................................................................................................................... 4 
1.2. 
Purpose ............................................................................................................................ 4 
2. 
Study objective ............................................................................................................ 4 
2.1. 
Primary objectives ............................................................................................................. 5 
2.2. 
Secondary objectives ......................................................................................................... 5 
2.3. 
Exploratory objectives ........................................................................................................ 6 
3. 
Investigational plan ..................................................................................................... 6 
3.1. 
Study design ...................................................................................................................... 6 
3.2. 
Rationale of study design ................................................................................................... 7 
3.3. 
Rationale of dose/regimen, route of administration, and duration of treatment ..................... 7 
3.4. 
Rationale for choice of comparator ..................................................................................... 8 
3.5. 
Purpose and timing of interim analyses/design adaptations ................................................. 8 
3.6. 
Risks and benefits ............................................................................................................. 8 
4. 
Population ................................................................................................................... 9 
4.1. 
Inclusion criteria ................................................................................................................ 9 
4.2. 
Exclusion criteria ............................................................................................................... 9 
4.3. 
Recruitment ...................................................................................................................... 9 
4.4. 
Sampling ........................................................................................................................... 9 
5. 
Treatment (intervention) .............................................................................................. 9 
5.1. 
Protocol requested treatment .......................................................................................... 10 
5.1.1. Investigational treatment ..................................................................................... 10 
5.1.2. Additional study treatment ................................................................................... 10 
5.2. 
Arms ............................................................................................................................... 10 
5.3. 
Randomization and arm assignment ................................................................................. 10 
5.4. 
Treating the participants .................................................................................................. 10 
5.4.1. Participant numbering ......................................................................................... 10 
5.4.2. Handling of study treatment ................................................................................. 10 
5.4.3. Instructions on study treatment ........................................................................... 10 
5.4.4. Permitted dose adjustments and interruptions of study treatment ......................... 10 
5.4.5. Rescue medication .............................................................................................. 10 
5.4.6. Concomitant treatment ....................................................................................... 11 
5.4.7. Prohibited treatment ........................................................................................... 11 
5.4. 
Premature participant withdrawal ..................................................................................... 11 
5.5. 
Study completion and post-study treatment...................................................................... 11 
6. 
Schedule and assessments ....................................................................................... 11 
6.1. 
Information to be collected on screening failures .............................................................. 11 
6.2. 
Participant demographics/other baseline characteristics .................................................. 11 
6.3. 
Treatment exposure and compliance ................................................................................ 12 
6.4. 
Efficacy ........................................................................................................................... 12 
6.5. 
Safety ............................................................................................................................. 12 
7. 
Safety monitoring ...................................................................................................... 12 
7.1. 
Adverse events ................................................................................................................ 12 

Digital Detox Study 
 
 
University for Continuing Education Krems 
Study Protocol 
 
 
 
 
 
 
page 3 of 18 
7.2. 
Serious adverse events .................................................................................................... 12 
8. 
Data review and database management ..................................................................... 12 
8.1. 
Site monitoring ................................................................................................................ 12 
8.2. 
Data collection ................................................................................................................ 12 
8.3. 
Database management and quality control ....................................................................... 13 
8.4. 
Data monitoring committee.............................................................................................. 13 
8.5. 
Adjudication committee ................................................................................................... 13 
9. 
Data analysis ............................................................................................................. 13 
9.1. 
Analysis sets ................................................................................................................... 13 
9.2. 
Participant demographics and other baseline characteristics ............................................ 13 
9.3. 
Treatments ...................................................................................................................... 14 
9.4. 
Analysis of primary variables ............................................................................................ 14 
9.4.1. Statistical model, hypotheses, and method analysis ............................................. 14 
9.4.2. Handling of missing values/censoring/discontinuations ........................................ 15 
9.4.3. Supportive analyses ............................................................................................ 15 
9.5. 
Analysis of secondary variables ........................................................................................ 15 
9.5.1. Efficacy variables ................................................................................................ 15 
9.5.2. Safety variables ................................................................................................... 15 
9.6. 
Interim analysis ............................................................................................................... 15 
9.7. 
Sample size calculation ................................................................................................... 15 
10. Ethical considerations ............................................................................................... 16 
10.1. Regulatory and ethical compliance ................................................................................... 16 
10.2. Informed consent procedures .......................................................................................... 16 
10.3. Responsibilities of the investigators and IRB/IEC ............................................................... 16 
10.4. Publication of study protocol and results .......................................................................... 16 
11. Protocol adherence ................................................................................................... 16 
11.1. Protocol amendments ..................................................................................................... 16 
12. References ................................................................................................................ 17 
 
 
 

Digital Detox Study 
 
 
University for Continuing Education Krems 
Study Protocol 
 
 
 
 
 
 
page 4 of 18 
1. Introduction 
1.1. Background 
The mental health of young people has deteriorated significantly in recent years. In 2022, as many as 73% 
of girls and 45% of boys in Austria suffered from moderate depressive symptoms (Haider et al., 2023). 
Other mental health symptoms were also very common, such as anxiety symptoms (57% among girls and 
35% among boys) or sleep problems (34% among girls, 21% among boys) (Haider et al., 2023). Although 
the causes of this development are undoubtedly multifactorial and individually different, daily smartphone 
use seems to have a particularly large influence (Humer et al., 2022). This is relevant because in many 
countries, including Austria, there has been a rapid increase in daily smartphone use: According to the 
HBSC study, the average time spent on a smartphone in 2022 was 5 hours a day, almost twice as much as 
in 2018 (Felder-Puig et al., 2021). In addition, there is at least a correlative link between screen time and 
mental health: A study of over 7,000 young people showed that the probability of depressive symptoms 
increased up to sevenfold with increasing smartphone usage time (Humer et al., 2022). Anxiety symptoms, 
sleep disorders, disordered eating behavior, and stress also increased with increasing screen time, while 
quality of life and well-being were reduced (Humer et al., 2022, Pieh et al., 2021). A stepwise effect can be 
seen: With each additional hour of daily screen time, the frequency of psychological symptoms increases 
and well-being decreases (Humer et al., 2022). 
A previous randomized controlled trial on the effect of smartphone use reduction on mental health in a 
relatively homogenous, sociodemographically advantaged, and healthy sample showed significant im-
provements in depression, well-being, stress, and sleep quality through a reduction in screen time (Pieh et 
al., 2025).  
1.2. Purpose 
The planned study aims to test this causal relationship in a larger and, above all, more diverse sample, and 
to make a more generalizable statement about the relationship. From a scientific point of view, the study 
offers the opportunity to examine the causality between smartphone use and psychological symptoms in 
a broader and more diverse sample and thus to test the generalizability of the previous results. From a 
social perspective, the findings can help to develop targeted prevention and intervention programs that 
aim to reduce screen time and promote mental health. At a time when digital devices are an integral part 
of everyday life, the study results could help to promote a more health-conscious relationship with tech-
nology and sustainably strengthen mental health. 
2. Study objective 
The aim of the Digital Detox study is to examine the effect of reduced smartphone use on mental health. 
The following primary research questions are addressed in the study: 
- 
How does a three-week reduction in smartphone use affect the depressive symptoms of the par-
ticipants? 
- 
How does a three-week reduction in smartphone use affect the sleep quality of the participants? 
- 
How does a three-week reduction in smartphone use affect the well-being of the participants? 
- 
How does a three-week reduction in smartphone use affect the perceived stress of the partici-
pants? 

Digital Detox Study 
 
 
University for Continuing Education Krems 
Study Protocol 
 
 
 
 
 
 
page 5 of 18 
2.1. Primary objectives 
The primary objective of the study is to examine the effect of smartphone reduction on mental health pa-
rameters: depressive symptoms, well-being, stress, and sleep quality. The following primary hypotheses 
are tested:  
- 
H1: Reducing smartphone use to  2 hours/day over 3 weeks leads to a difference in the depres-
sive symptoms of the intervention participants before (t0) and after participating in the interven-
tion (t1). 
- 
H2: Reducing smartphone use to  2 hours/day over 3 weeks leads to a difference in the sleep 
quality of the intervention participants before (t0) and after participating in the intervention (t1). 
- 
H3: Reducing smartphone use to  2 hours/day over 3 weeks leads to a difference in perceived 
stress of the intervention participants before (t0) and after participating in the intervention (t1). 
- 
H4: Reducing smartphone use to  2 hours/day over 3 weeks leads to a difference in the well-be-
ing of the intervention participants before (t0) and after participating in the intervention (t1). 
- 
H5: The reduction in smartphone use to  2 hours/day over 3 weeks led to a difference in depres-
sive symptoms between the control and intervention groups at the post-intervention time point 
(t1). 
- 
H6: The reduction in smartphone use to  2 hours/day over 3 weeks led to a difference in sleep 
quality between the control and intervention groups at the post-intervention time point (t1). 
- 
H7: The reduction in smartphone use to  2 hours/day over 3 weeks led to a difference in per-
ceived stress between the control and intervention groups at the post-intervention time point 
(t1). 
- 
H8: The reduction in smartphone use to  2 hours/day over 3 weeks led to a difference in well-
being between the control and intervention groups at the post-intervention time point (t1).  
2.2. Secondary objectives 
The secondary objective focuses on loneliness, craving, and physical activity. The following hypotheses are 
tested:  
- 
H9: Reducing smartphone use to  2 hours/day over 3 weeks leads to a difference in the loneli-
ness of the intervention participants before (t0) and after participating in the intervention (t1). 
- 
H10: The reduction in smartphone use to  2 hours/day over 3 weeks led to a difference in loneli-
ness between the control and intervention groups at the post-intervention time point (t1). 
- 
H11: Reducing smartphone use to  2 hours/day over 3 weeks leads to a difference in the physi-
cal activity of the intervention participants before (t0) and after participating in the intervention 
(t1). 
- 
H12: The reduction in smartphone use to  2 hours/day over 3 weeks led to a difference in physi-
cal activity between the control and intervention groups at the post-intervention time point (t1). 
- 
H13: Reducing smartphone use to  2 hours/day over 3 weeks leads to a difference in craving of 
the intervention participants before (t0) and after participating in the intervention (t1). 
- 
H14: The reduction in smartphone use to  2 hours/day over 3 weeks led to a difference in craving 
between the control and intervention groups at the post-intervention time point (t1). 
 

Digital Detox Study 
 
 
University for Continuing Education Krems 
Study Protocol 
 
 
 
 
 
 
page 6 of 18 
2.3. Exploratory objectives 
The influence of smartphone use, i.e. how the smartphone is used during the period of reduction and in 
which areas the most reduction takes place, as well as craving, loneliness, and physical activity on the 
primary outcome parameters of mental health (see 2.1) will be explored.  
3. Investigational plan  
3.1. Study design 
The Digital Detox study is designed as a randomized controlled trial with two unblinded, parallel arms (in-
tervention group and control group). Participants will be randomly assigned to two groups. Randomization 
will take place after an initial eligibility screening. The screening takes place when participants enter the 
study after they have given their informed consent to participate. After the randomization, the intervention 
group will start the intervention, a three-week digital detox in which smartphone use is to be reduced to  
2 hours per day, while the control group continues to use their smartphone as before. The intervention 
phase starts on a Monday and ends on a Sunday three weeks later (see Schedule below). On the Sunday, 
before the start of the intervention, the mental health parameters (depressive symptoms (PHQ-9), sleep 
quality (ISI), stress (PSQ-20), well-being (WHO-5), loneliness (three-item loneliness scale), craving (CEQ-
F), and physical activity) are measured (baseline survey, t0). At the end of the intervention (Sunday three 
weeks later), these are measured again (post-intervention survey, t1). After the end of the intervention, the 
intervention group also returns to their normal, unrestricted smartphone use. Three weeks after the end of 
the intervention (again on a Sunday), a follow-up survey of the mental health parameters (same as for t0 
and t1) takes place (follow-up survey, t2). Baseline, post-intervention and follow-up surveys take place in 
parallel for both groups. Both groups will also complete items on loneliness and physical activity twice 
during the intervention (after the first and second week of the intervention) to monitor changes in these 
variables during the intervention. From the beginning of the intervention (t0) until the follow-up time point 
(t2), the smartphone screen time of the past week, the smartphone activations, and the most frequently 
used apps are recorded in the study app via self-report and uploading a screenshot every Monday. Monday 
was chosen to have a complete picture of the past week’s smartphone usage behavior. The study will be 
performed entirely via a smartphone app (ESMira), which is designed especially to run longitudinal studies.  
 
 

Digital Detox Study 
 
 
University for Continuing Education Krems 
Study Protocol 
 
 
 
 
 
 
page 7 of 18 
The following variables are collected in the study:  
Assessed only in the screening: 
- 
Sociodemographic variables: Age (in years), gender, country of residence, highest completed ed-
ucation, current educational/employment status, urban/rural classification of residence. 
- 
Mental health (self-report): 
o 
Do you have a mental health condition for which you are currently receiving treatment? 
(yes/no) 
o 
Are you currently taking medication for a mental health condition? (yes/no) 
o 
Smartphone usage: Do you use your smartphone for an average of ≥3 hours per day? 
(yes/no) 
Assessed in screening and at all subsequent time points (t0, t1, t2): 
- 
Depressive Symptoms (PHQ-9): The Patient Health Questionnaire (PHQ-9) is used to assess de-
pressive symptoms in its validated German version, consisting of 9 items (Kroenke et al., 2001; 
Löwe et al., 2004). 
- 
Well-being (WHO-5): The validated German version of the World Health Organization Well-Being 
Index (WHO-5) is used to assess participants’ well-being and consists of 5 items (Brähler et al., 
2007; Topp et al., 2015). 
- 
Sleep Quality (ISI): The Insomnia Severity Index (ISI) is used in its validated German version to as-
sess the quality of sleep and consists of 7 items (Bastien et al., 2001; Gerber et al., 2016; Morin et 
al., 2001). 
- 
Stress (PSQ-20): Stress is assessed using the German version of the short form of the Perceived 
Stress Questionnaire (PSQ-20), which consists of 20 items (Fliege et al., 2009; Fliege et al.; 2005; 
Levenstein et al., 1993). 
- 
Loneliness (3-Item Loneliness Questionnaire): Loneliness is assessed using the German version 
of the Three Items Loneliness Scale, consisting of 3 items (Klein et al., 2021; Reinwarth et al., 
2024). 
- 
Physical activity: “On how many of the last 7 days were you physically active for at least 60 
minutes?” and “How many minutes did you spend doing sport in the last 7 days?” 
- 
Craving (CEQ-F) [not in screening]: Craving is measured using the Craving Experience Question-
naire (CEQ-F) in the German version, for behavioral addictions and smartphone use in particular, 
and consists of 9 items (Brandtner & Wegmann, 2023; Cornil et al., 2019; Fritz, n.d.). 
- 
Smartphone use (self-report and upload of screenshots of screen time over the last week, activa-
tions, and the most frequently used apps).  
3.2. Rationale of study design 
It is an unblinded two-armed study because the participants are informed about their group allocation be-
fore the start of the intervention. This is necessary so that they can reduce their smartphone screen time if 
they are in the intervention group.  
3.3. Rationale of dose/regimen, route of administration, and duration of treatment 
Rationale of dose/regimen, route of administration: not applicable. 
The intervention period is based on the previous study (Pieh et al., 2025).  

Digital Detox Study 
 
 
University for Continuing Education Krems 
Study Protocol 
 
 
 
 
 
 
page 8 of 18 
3.4. Rationale for choice of comparator 
The control group with its unchanged usage behavior is used as a comparator to allow insights into “nor-
mal” smartphone usage behavior.  
3.5. Purpose and timing of interim analyses/design adaptations 
Not applicable.  
3.6. Risks and benefits 
The preceding study clearly indicates an improvement in well-being, depression, sleep quality, and stress 
due to the three-week screen time reduction (Pieh et al., 2025). In addition, a higher awareness of one's 
own media use is to be expected. It can be assumed that participants will gain a better understanding of 
their habits by examining their smartphone use. This awareness can help them to develop a healthier bal-
ance between online and offline activities in the long term. Continuous monitoring during the course of the 
study gives participants a regular overview of their mental health and well-being. The opportunity to ob-
serve changes in these parameters can have a motivating effect and promote commitment to sustainable 
improvement. 
Even if preliminary studies indicate a positive effect of the intervention on mental health (Pieh et al., 2025), 
it cannot be ruled out that in individual cases mental health may also deteriorate during the intervention. 
In this case, study participants have the opportunity to contact psychologists from the study team directly 
via ESMira, without jeopardizing their anonymity. In this case, the contact persons provide information on 
low-threshold psychological and psychotherapeutic resources in the respective country. The study team 
maintains a central document, stored on the UWK server, in which adverse effects and their handling are 
systematically documented.  
To prevent foreseeable undesirable effects, transparent communication about the content and objectives 
of the study takes place in advance. In addition, the study refrains from complete smartphone abstinence, 
since this may increase the risk of stress, loneliness, or other psychological stress. Furthermore, the study 
team does not intervene in the smartphone settings of the participants. The guidelines for maximum daily 
screentime are to be adhered to independently by the participants. Non-compliance is not subject to sanc-
tions. 
To ensure the safety and well-being of the participants, a written explanation of the objectives and the 
course of the study will be provided. The consent of the participants to participate in the study will be ob-
tained. During the study, participants will have the opportunity to contact the study team via a message in 
ESMira and to report any unwanted effects (e.g. deterioration in mental health). Psychologists from the re-
search team have been defined as the primary contact persons. Participants may withdraw from the study 
at any time and without having to expect negative consequences. Participants will be informed of this right 
before they take part in the study. The study team will also be available as a point of contact even after they 
have withdrawn or left the study. 
Measures in the event of foreseeable adverse effects include the provision of resources for low-threshold 
psychological and psychotherapeutic services. Furthermore, participants can withdraw from the study at 
any time without negative consequences. Participants are informed of this right before participating in the 

Digital Detox Study 
 
 
University for Continuing Education Krems 
Study Protocol 
 
 
 
 
 
 
page 9 of 18 
study. The responsibility for discontinuing lies with the study participants themselves, while the study team 
provides the framework for discontinuing without consequences.  
4. Population 
German-speaking adults of any gender can participate in the study. The inclusion and exclusion criteria 
are presented below:  
4.1. Inclusion criteria 
Participants must fulfill the following criteria for study participation: 
- 
At least 18 years old 
- 
Sufficient skills in German  
- 
Daily smartphone use of  3 hours  
- 
No ongoing psychotherapeutic, psychological or psychopharmacological treatment 
4.2. Exclusion criteria 
The following persons are not allowed to participate:  
- 
Under 18 years old 
- 
Insufficient skills in German 
- 
Daily smartphone use  3 hours 
- 
In ongoing psychotherapeutic, psychological, or psychopharmacological treatment 
4.3. Recruitment 
Participants will be recruited via the university’s and the department's social media channels (Instagram: 
istokay.at and unikrems, and X (formerly Twitter): @PsychUniKrems). These will be used to post and upload 
stories to provide information about the study. Furthermore, e-mails with information will be sent to uni-
versities, colleges, and other educational institutions and associations. The main channel for recruitment 
will be social media channels.  
4.4. Sampling 
Convenience sampling is used to recruit participants. The recruitment channels are described above (4.3).  
Via a link or associated QR code, interested persons can access the study page on ESMira, where they 
electronically give informed consent to participate in the study and subsequently access the eligibility 
screening questionnaire, which also asks about the inclusion and exclusion criteria of the study (see 4.1 
and 4.2).  
5. Treatment (intervention) 
The intervention consists of reducing one's daily smartphone screen time to a maximum of two hours for 
three consecutive weeks.  

Digital Detox Study 
 
 
University for Continuing Education Krems 
Study Protocol 
 
 
 
 
 
 
page 10 of 18 
5.1. Protocol requested treatment 
5.1.1. Investigational treatment  
The study assessed the variables described under 3.1. 
5.1.2. Additional study treatment  
No additional study treatments beyond the investigational treatment are requested for this trial.  
5.2. Arms 
The study has two parallel unblinded arms (control group and intervention group): 
1. The intervention group reduces their daily smartphone screen time to a maximum of 2 hours dur-
ing the three-week intervention.  
2. The control group continues to use their smartphone as usual during the intervention phase.  
5.3. Randomization and arm assignment  
The method of simple randomization is used to assign participants to the two arms purely at random. Ran-
domization takes place after screening. Participants will be informed of the allocation to the arm before 
the start of the intervention by a message in the ESMira app. All instructions for the intervention period (i.e. 
reduction of screentime for the intervention group and unrestricted use for the control group) will also be 
provided in this message.  
5.4. Treating the participants 
5.4.1. Participant numbering 
The anonymity of the participants is ensured in ESMira by a randomly generated user ID (12 numbers/let-
ters, e.g. 4mZm-F8vN-5Vyk).Dispensing the investigational treatment 
5.4.2. Handling of study treatment 
Not applicable. Handling of investigational treatment 
5.4.3. Instructions on study treatment 
Participants will receive instructions on what to do during the intervention period via a message in ESMira 
before the start of the intervention.  
5.4.4. Permitted dose adjustments and interruptions of study treatment 
Not applicable.  
5.4.5. Rescue medication 
Not applicable.  

Digital Detox Study 
 
 
University for Continuing Education Krems 
Study Protocol 
 
 
 
 
 
 
page 11 of 18 
5.4.6. Concomitant treatment 
Not applicable.  
5.4.7. Prohibited treatment 
Not applicable.  
5.4. 
Premature participant withdrawal  
Participants can withdraw from the study at any time without giving reasons and without negative conse-
quences. To do so, they only have to leave the study in the ESMira app.  
5.5. 
Study completion and post-study treatment 
For both groups, participation in the study is completed after they have provided information on their 
smartphone use at the follow-up point in time (t2). After the study, the study team will be available to an-
swer questions via the email addresses provided. The control group has the option of participating in the 
intervention after t2 in order to also benefit from the expected positive effects on mental health.  
6. 
Schedule and assessments 
The table below lists all assessments from eligibility screening to follow-up (t2). The respective questions 
and questionnaires are described under 3.1. 
 
6.1. 
Information to be collected on screening failures 
All patients who give informed consent to participate in the study but discontinue at baseline (t0) are con-
sidered screening failures. Information on the reasons for discontinuation will not be collected.  
6.2. 
Participant demographics/other baseline characteristics 
Participants’ sociodemographic characteristics (described under 3.1) will be assessed at the eligibility 
screening. Baseline data will be collected at t0, right before the start of the intervention.  

Digital Detox Study 
 
 
University for Continuing Education Krems 
Study Protocol 
 
 
 
 
 
 
page 12 of 18 
6.3. 
Treatment exposure and compliance 
The intervention in the form of screen-time reduction is regarded as treatment in this study. The interven-
tion group exposes itself to this intervention. Compliance with the maximum screen time can be checked 
using the weekly screen-time data (screenshots).  
6.4. 
Efficacy  
Not applicable.  
6.5. 
Safety 
Not appliable.  
7. Safety monitoring 
7.1. 
Adverse events  
An adverse event (AE) is any unfavorable medical occurrence (i.e., any unfavorable and unintended sign in 
a clinical trial participant after written informed consent for participation in the study. Therefore, an AE may 
or may not be temporally or causally associated with the intervention. One possible AE could be a deteri-
oration in mental health. Measures have been referred to under 3.6.   
7.2. 
Serious adverse events 
No serious AE adverse events to be expected. 
8. Data review and database management 
8.1. 
Site monitoring 
Not applicable.  
8.2. 
Data collection 
This is a purely web-based study. The data will be collected using the ESMira application. Questionnaires 
are scheduled to appear directly in the app at pre-set times and participants receive a notification that they 
must be completed. Screenshots of smartphone usage are also uploaded in the app.  
Data collection and communication with the participants takes place exclusively via the research applica-
tion ESMira. ESMira can be installed on all smartphones and was developed specifically for scientific stud-
ies (especially with longitudinal design). The app not only allows questionnaires to be sent at pre-set times, 
but also enables completely anonymous communication with the participants. No permanent internet 
connection is required to use the ESMira app. Completed questionnaires are stored locally in the app and 
automatically uploaded as soon as an internet connection is available. The research data is stored in en-
crypted form on a server at the University for Continuing Education Krems. The anonymity of the partici-
pants is ensured in ESMira by a randomly generated user-id (12 numbers/letters, e.g. 4mZm-F8vN-5Vyk). 
Further information about ESMira can be found under: https://github.com/KL-Psychological-Methodology/ 

Digital Detox Study 
 
 
University for Continuing Education Krems 
Study Protocol 
 
 
 
 
 
 
page 13 of 18 
8.3. 
Database management and quality control 
Data is stored directly on the university server. In agreement with the data protection officers, the personal 
data will only be stored for the duration of the study. After that, the data will be stored in a completely 
anonymized form (deletion of all personal data) without any time limit. Access to the raw research data is 
restricted to the scientific team at the Center for Mental Health Research at the University for Continuing 
Education Krems. App developers are not able to access the study data. 
Participants can contact the study team anonymously via ESMira and register that they would like to have 
access to their study-relevant personal data. In this case, the data protection officers will be contacted to 
ensure a legally correct process. 
In accordance with Art. 32 DSGVO, appropriate technical and organizational measures are taken to protect 
personal data. All scientific staff involved in the research project are bound to data secrecy and regularly 
take part in data protection awareness training. Only the scientific staff of the Center for Mental Health 
Research will have access to the raw research data. The data is stored on a local server at the university 
with access protection. Unauthorized reading, copying, modifying, or deleting is thus not possible. Further-
more, the data is only collected and stored in pseudonymized form. The personal data will only be stored 
for the duration of the study. After that, it will only be stored in a completely anonymized form. 
8.4. 
Data monitoring committee 
Not applicable.  
8.5. 
Adjudication committee  
Not applicable. 
9. Data analysis  
The data analysis will be performed by the researcher at the Center of Mental Health Research at the Uni-
versity for Continuing Education Krems. Unless otherwise specified, all statistical tests will be conducted 
against a two-sided alternative hypothesis with a significance level of  = 5%. Participants who discontin-
ued the study at the baseline time point (t0) will be excluded from the analysis. Following the intention-to-
treat principle, participants will be primarily analyzed according to their arm allocation. Exploratory anal-
yses per-protocol are also possible.  
9.1. 
Analysis sets 
There will be only one analysis set containing all collected data.   
9.2. 
Participant demographics and other baseline characteristics 
The following variables are collected in the study:  
Assessed only in the screening: 
- 
Sociodemographic variables: Age (in years), gender, country of residence, highest completed ed-
ucation, current educational/employment status, urban/rural classification of residence. 
- 
Mental health (self-report): 

Digital Detox Study 
 
 
University for Continuing Education Krems 
Study Protocol 
 
 
 
 
 
 
page 14 of 18 
o 
Do you have a mental health condition for which you are currently receiving treatment? 
(yes/no) 
o 
Are you currently taking medication for a mental health condition? (yes/no) 
o 
Smartphone usage: Do you use your smartphone for an average of ≥3 hours per day? 
(yes/no) 
Assessed in screening and at all subsequent time points (t0, t1, t2): 
- 
Depressive Symptoms (PHQ-9): The Patient Health Questionnaire (PHQ-9) is used to assess de-
pressive symptoms in its validated German version, consisting of 9 items (Kroenke et al., 2001; 
Löwe et al., 2004). 
- 
Well-being (WHO-5): The validated German version of the World Health Organization Well-Being 
Index (WHO-5) is used to assess participants’ well-being and consists of 5 items (Brähler et al., 
2007; Topp et al., 2015). 
- 
Sleep Quality (ISI): The Insomnia Severity Index (ISI) is used in its validated German version to as-
sess the quality of sleep and consists of 7 items (Bastien et al., 2001; Gerber et al., 2016; Morin et 
al., 2001). 
- 
Stress (PSQ-20): Stress is assessed using the German version of the short form of the Perceived 
Stress Questionnaire (PSQ-20), which consists of 20 items (Fliege et al., 2009; Fliege et al.; 2005; 
Levenstein et al., 1993). 
- 
Loneliness (3-Item Loneliness Questionnaire): Loneliness is assessed using the German version 
of the Three Items Loneliness Scale, consisting of 3 items (Klein et al., 2021; Reinwarth et al., 
2024). 
- 
Physical activity: “On how many of the last 7 days were you physically active for at least 60 
minutes?” and “How many minutes did you spend doing sport in the last 7 days?” 
- 
Craving (CEQ-F) [not in screening]: Craving is measured using the Craving Experience Question-
naire (CEQ-F) in the German version, for behavioral addictions and smartphone use in particular, 
and consists of 9 items (Brandtner & Wegmann, 2023; Cornil et al., 2019; Fritz, n.d.). 
- 
Smartphone use (self-report and upload of screenshots of screen time over the last week, activa-
tions, and the most frequently used apps).  
9.3. 
Treatments 
The intervention acts as a treatment. During the intervention, the smartphone screen time of the inter-
vention group is reduced to a maximum of 2 hours per day for three weeks.  
9.4. 
Analysis of primary variables 
9.4.1. Statistical model, hypotheses, and method analysis 
 χ2-Test and independent samples t-tests will be used to examine differences regarding sociodemographic 
variables and mental health indicators (see 9.2) between the control and intervention group. 
In order to examine the effect of smartphone screen time reduction on the participants’ mental health (see 
2.1), repeated measures ANOVAs (rm-ANOVAs) will be performed. The primary hypotheses focus on the 
difference between the baseline and the post-intervention time points (t0 – t1) in the intervention group as 
well as on the difference between the control and the intervention group at t1. An intention-to-treat analy-
sis will be carried out. Arm allocation (control group or intervention group) will be the between-group factor. 

Digital Detox Study 
 
 
University for Continuing Education Krems 
Study Protocol 
 
 
 
 
 
 
page 15 of 18 
Time (t0, t1) will be the within-group factor. Effect sizes will be presented as partial eta squared 
(η2 = time × group) or group mean differences. 
In a secondary analysis, the difference between the baseline (t0), the post-intervention (t1), and the follow-
up time points (t2) in the intervention group as well as the difference between the control and the interven-
tion group at t2 will be additionally examined using the same statistical approach.  
In case of baseline group differences, the respective variables will be added as covariates in the rm-ANO-
VAs. If the sphericity assumptions are violated, corrections will be applied. Corrections for multiple com-
parisons will be applied in the post-hoc pairwise comparisons.  
Percentage changes in the mental health outcomes between the time points will be calculated (Hurst & 
Bolton, 2004).  
Furthermore, subgroup analyses are planned, especially of the subgroup from the intervention group that 
strictly adhered to the screentime limit (per-protocol), but also with regard to sociodemographic variables 
(e.g., gender or age) or pre-intervention (t0) mental health parameter scores. The analysis is performed as 
described above. Due to the planned subgroup analyses, a larger sample is also aimed for than is intended 
in the sample size calculation for the main analysis.  
9.4.2. Handling of missing values/censoring/discontinuations 
Assuming that the respective assumptions are met, missing values will be dealt with using maximum like-
lihood estimation.   
9.4.3. Supportive analyses  
Not applicable.  
9.5. 
Analysis of secondary variables  
The same statistical analysis methods as for the primary variables will be applied (see 9.4).  
9.5.1. Efficacy variables 
Not applicable.  
9.5.2. Safety variables 
Not applicable.  
9.6. 
Interim analysis 
No interim analysis is planned.  
9.7. 
Sample size calculation 
The calculation for the required sample size to detect potential effects was carried out using G*Power. The 
following parameters were set for an rm-ANOVA with within-between interaction: error probability  = 5%, 

Digital Detox Study 
 
 
University for Continuing Education Krems 
Study Protocol 
 
 
 
 
 
 
page 16 of 18 
power = 90%, effect size partial 2 = 0.05, number of groups = 2, number of measurements = 2, correlation 
among repeated measures = 0.5, and nonsphericity correction ε = 1 (based on the preliminary study from 
Pieh et al., 2025). The sample size calculation resulted in a total sample of at least 52 participants. A drop-
out rate of 40% is expected, hence at least 87 participants must be recruited. The aim is to recruit a sample 
that is as large and diverse as possible (minimum target: approx. 200 participants). In order to have a suf-
ficiently large sample for planned subgroup analyses, the target is approximately 500 participants.  
10. Ethical considerations 
10.1. Regulatory and ethical compliance 
The study will be conducted in accordance with the guidelines of the Declaration of Helsinki and CONSORT 
guidelines for non-pharmacological trials. The ethics committee of the University for Continuing Education 
Krems approved the study’s ethics application on December 12, 2024 (EK_GZ_15_2024-2027).  
10.2. Informed consent procedures 
Informed consent will be obtained from all participants upon entering the study in the ESMira app, before 
filling in any questionnaires. Participants will give their consent to participate electronically in ESMira. In-
formation on informed consent (information about the study and data protection declaration) will be pre-
sented in German. An English translation of it will be provided with the study registration.  
10.3. Responsibilities of the investigators and IRB/IEC 
The IEC (ethics committee of the University for Continuing Education Krems) received the study protocol, 
the written informed consent form, information about the recruitment, information about the compensa-
tion for subjects (none), all questionnaires intended to be used, a study timeline as well as information 
about the research app (ESMira). The IEC has reviewed the documents to determine whether the study 
complies with the ethical guidelines and has assessed it positively.  
The ethics committee will be informed about the progress and results of the study.  
10.4. Publication of study protocol and results 
Key elements of this study protocol will be published in a publicly accessible database for study registra-
tions (clinicaltrials.gov). Upon study completion and finalization of the study report, the results of this 
study will be submitted to scientific journals for publication.  
11. Protocol adherence 
The study objectives, the study procedure (schedule), and the data to be collected are defined in this study 
protocol. Investigators will ensure that they use due diligence to avoid protocol deviations. If an investigator 
believes that a protocol deviation would improve the conduct of the study, these will be considered proto-
col amendments. Such a modification will only be made after IEC approval.  
11.1. Protocol amendments 
Any changes to the protocol will only be made in written form after the approval of the IEC.  

Digital Detox Study 
 
 
University for Continuing Education Krems 
Study Protocol 
 
 
 
 
 
 
page 17 of 18 
12. References 
Bastien, C. H., Vallières, A., & Morin, C. M. (2001). Validation of the Insomnia Severity Index as an out-
come measure for insomnia research. Sleep Medicine, 2(4), 297-307. https://doi.org/10.1016/s1389-
9457(00)00065-4 
Brähler, E., Mühlan, H., Albani, C., & Schmidt, S. (2007). Teststatistische Prüfung und Normierung der 
deutschen Versionen des EUROHIS-QOL Lebensqualität-Index und des WHO-5 Wohlbefindens-Index. 
Diagnostica, 53(2), 83-96. https://doi.org/10.1026/0012-1924.53.2.83 
Brandtner, A., & Wegmann, E. (2023). The fear in desire: linking desire thinking and fear of missing out in 
the social media context. BMC Psychology, 11(1), 176. 
Cornil, A., Long, J., Rothen, S., Perales, J. C., de Timary, P., & Billieux, J. (2019). The gambling craving expe-
rience questionnaire: Psychometric properties of a new scale based on the elaborated intrusion theory of 
desire. Addictive Behaviors, 95, 110-117. 
Felder-Puig, R., Soede, I., & Winkler, R. (2021): Wohlbefinden der österreichischen Schülerinnen und 
Schüler in der Schule. HBSC-Factsheet 09: Ergebnisse der HBSC-Studie 2018. Bundesministerium für 
Soziales, Gesundheit, Pflege und Konsumentenschutz, Wien. 
Fliege, H., Rose, M., Arck, P., Levenstein, S., & Klapp, B. F. (2009). PSQ – Perceived Stress Questionnaire. 
In. Leibniz Institute for Psychology – Open Test Archive. https://doi.org/https://doi.org/10.23668/psychar-
chives.5138 
Fliege, H., Rose, M., Arck, P., Walter, O. B., Kocalevent, R.-D., Weber, C., & Klapp, B. F. (2005). The Per-
ceived Stress Questionnaire (PSQ) Reconsidered: Validation and reference values from different clinical 
and healthy adult samples. Psychosomatic Medicine, 67(1). 
https://doi.org/10.1097/01.psy.0000151491.80178.78 
Fritz, M. The Craving Experience Questionnaire: Validation of a German Version. Gerber, M., Lang, C., 
Lemola, S., Colledge, F., Kalak, N., Holsboer-Trachsler, E., Pühse, U., & Brand, S. (2016). Validation of the 
German version of the Insomnia Severity Index in adolescents, young adults and adult workers: results 
from three crosssectional studies. BMC Psychiatry, 16, 174. https://doi.org/10.1186/s12888-016-0876-8 
Haider, K., Humer, E., Weber, M., Pieh, C., Ghorab, T., Dale, R., Dinhof, C., Gächter, A., Probst, T., & Jesser, 
A. (2023). An Assessment of Austrian School Students’ Mental Health and Their Wish for Support: A Mixed 
Methods Approach. International Journal of Environmental Research and Public Health, 20(6), 4749. 
https://doi.org/10.3390/ijerph20064749 
Humer, E., Probst, T., Wagner-Skacel, J., & Pieh, C. (2022). Association of Health Behaviors with Mental 
Health Problems in More than 7000 Adolescents during COVID-19. International Journal of Environmental 
Research and Public Health, 19(15), 0–5. https://doi.org/10.3390/ijerph19159072 
Hurst, H., & Bolton, J. (2004). Assessing the clinical significance of change scores recorded on subjective 
outcome measures. Journal of Manipulative and Physiological Therapeutics, 27(1), 26–35. 
https://doi.org/10.1016/j.jmpt.2003.11.003 

Digital Detox Study 
 
 
University for Continuing Education Krems 
Study Protocol 
 
 
 
 
 
 
page 18 of 18 
Klein, E. M., Zenger, M., Tibubos, A. N., Ernst, M., Reiner, I., Schmalbach, B., ... & Beutel, M. E. (2021). 
Loneliness and its relation to mental health in the general population: Validation and norm values of a 
brief measure. Journal of Affective Disorders Reports, 4, 100120. 
Kroenke, K., Spitzer, R. L., & Williams, J. B. (2001). The PHQ-9: validity of a brief depression severity meas-
ure. Journal of General Internal Medicine, 16(9), 606-613. https://doi.org/10.1046/j.1525-
1497.2001.016009606.x 
Levenstein, S., Prantera, C., Varvo, V., Scribano, M. L., Berto, E., Luzi, C., & Andreoli, A. (1993). Develop-
ment of the perceived stress questionnaire: A new tool for psychosomatic research. Journal of Psychoso-
matic Research, 37(1), 19-32. https://doi.org/https://doi.org/10.1016/0022-3999(93)90120-5 
Löwe, B., Spitzer, R. L., Gräfe, K., Kroenke, K., Quenter, A., Zipfel, S., Buchholz, C., Witte, S., & Herzog, W. 
(2004). Comparative validity of three screening questionnaires for DSM-IV depressive disorders and phy-
sicians’ diagnoses. Journal of Affective Disorders, 78(2), 131-140. https://doi.org/10.1016/S0165-
0327(02)00237-9 
Morin, C. M., Belleville, G., Bélanger, L., & Ivers, H. (2011). The Insomnia Severity Index: psychometric in-
dicators to detect insomnia cases and evaluate treatment response. Sleep, 34(5), 601-608. 
https://doi.org/10.1093/sleep/34.5.601 
Pieh, C., Humer, E., Hoenigl, A., Schwab, J., Mayerhofer, D., Dale, R., & Haider, K. (2025). Smartphone 
screen time reduction improves mental health: a randomized controlled trial. BMC Medicine, 23(1), 107. 
https://doi.org/10.1186/s12916-025-03944-z 
Pieh, C., Plener, P. L., Probst, T., Dale, R., & Humer, E. (2021). Assessment of mental health of high school 
students during social distancing and remote schooling during the COVID-19 pandemic in Austria. JAMA 
Network Open, 4(6), e2114866-e2114866. 
Reinwarth, A. C., Petersen, J., Beutel, M. E., Hautzinger, M., & Brähler, E. (2024). Social support in older 
adults: Validation and norm values of a brief form of the Perceived Social Support Questionnaire (F-SozU 
K-6). Plos one, 19(3), e0299467. 
Topp, C. W., Østergaard, S. D., Søndergaard, S., & Bech, P. (2015). The WHO-5 Well- Being Index: A Sys-
tematic review of the literature. Psychotherapy and Psychosomatics, 84(3), 167-176. 
https://doi.org/10.1159/000376585