University students experience high rates of psychological distress and frequently encounter barriers to accessing professional mental health support. Web-based interventions may provide a scalable and accessible approach for promoting mental health and well-being in university settings. Acceptance and Commitment Therapy (ACT) is a transdiagnostic behavioural intervention that aims to increase psychological flexibility and has demonstrated beneficial effects on a range of psychological and academic outcomes among university students.

YOLO (You Only Live Once) is a four-week, self-guided, web-based ACT mental health promotion program developed for university students. Previous pilot and randomized controlled evaluations of YOLO demonstrated significant improvements in psychological well-being, distress, and academic functioning. Following these encouraging findings, YOLO was integrated into the University of Queensland's suite of digital well-being resources for students, and the present study was designed to evaluate its university-wide implementation using a prospective single-arm interventional approach.

The study aims to evaluate the preliminary effectiveness of the YOLO program in improving psychological distress, well-being, life satisfaction, academic performance, and psychological flexibility/inflexibility processes. In addition, the study will examine the feasibility, acceptability, usability, and engagement associated with participation in the intervention and investigate whether changes in psychological flexibility/inflexibility processes are associated with improvements in mental health and well-being outcomes. Findings from this study are expected to inform the future implementation and dissemination of web-based ACT interventions within university settings.

Mental health concerns among university students represent an important public health issue. International epidemiological studies indicate that approximately 19.2% to 50% of university students meet the diagnostic criteria for at least one mental health disorder. Despite the high prevalence of psychological difficulties, a substantial proportion of affected students do not seek professional support, with estimates ranging from 65% to 85%. At the same time, university counselling and health services have reported increasing demand, increasing clinical complexity, and insufficient resources to adequately address student needs.

The widespread use of online resources by university students for obtaining health-related information and support suggests that web-based delivery may provide a feasible and acceptable approach to mental health promotion. In addition to increasing accessibility, web-based interventions may overcome common barriers to seeking support, such as perceived stigma, time constraints, and competing academic responsibilities. Previous research has further demonstrated that highly distressed university students often report a preference for web-based psychological interventions.

The wide range of psychological difficulties experienced by university students suggests that interventions targeting common underlying processes across symptoms may be particularly appropriate. Although digital mental health interventions have demonstrated effectiveness across various conditions, many existing programs are designed for specific disorders and may therefore have limited utility in universal student populations. In addition, interventions that focus primarily on symptom reduction do not necessarily promote the development of positive psychological resources and skills associated with flourishing and optimal functioning. Consequently, transdiagnostic interventions that target shared risk and protective processes may offer a more comprehensive framework for promoting mental health and well-being among university students.

Acceptance and Commitment Therapy (ACT) is an empirically supported transdiagnostic intervention that aims to enhance psychological flexibility. A substantial body of evidence supports the effectiveness of ACT in improving mental health and well-being outcomes across adult populations. Evidence from university settings has also demonstrated promising outcomes for ACT-based interventions. Among university students, participation in ACT programs has been associated with improvements in psychological flexibility, self-compassion, educational values, and academic outcomes, including academic performance and grade point average. ACT-based interventions have also been linked to reductions in anxiety, depression, stress, and broader psychological distress.

The present study uses a prospective single-arm interventional design to evaluate the university-wide implementation of the program. All participants will receive immediate access to the same four-week web-based intervention and no control condition will be included. To support both implementation and evaluation objectives, participants may enrol in one of two assessment pathways. The Full research Arm includes assessments at T1 (baseline/pre-intervention), T2 (post-intervention, 4 weeks), and T3 (3-month follow-up). Data obtained from this pathway will be used to evaluate preliminary effectiveness, feasibility, acceptability, usability, and potential mechanisms of change associated with participation in the program. Participants enrolled in the Minimal research Arm will complete a brief baseline assessment prior to accessing the intervention. Data collected through this pathway will be used exclusively for descriptive and implementation purposes, including the evaluation of program reach, uptake, and engagement. The two pathways differ only in the extent of assessment and follow-up procedures and do not represent different intervention conditions. Only participants enrolled in the Full research Arm will contribute data to the effectiveness analyses and the examination of potential mechanisms of change.

Participant email addresses will be used solely for study administration purposes, including sending automated reminders and invitations to complete follow-up assessments. Personally identifiable information will not be linked to survey responses or disclosed to individuals outside the research team. All data will be stored securely in de-identified and aggregated formats in accordance with institutional data management procedures.

The study hypothesises that participation in YOLO will be associated with improvements in psychological distress, well-being, life satisfaction, academic outcomes, and psychological flexibility/inflexibility processes, including experiential Avoidance, cognitive defusion, valued living, education values, and present-moment awareness. Changes in outcomes will be examined using repeated-measures analyses across assessment time points. Potential mechanisms of change will be investigated by examining whether changes in psychological flexibility/inflexibility processes mediate changes in primary outcomes. Findings from both assessment pathways will be used to inform future implementation and dissemination of the YOLO program within university settings, and the results will be disseminated through scientific publications and reports.

Inclusion Criteria:

1. Currently enrolled student at the University of Queensland.
2. Aged 18 years or older.
3. Sufficient computer and internet literacy;
4. Fluent knowledge of the English language.
5. Able to access the web-based platform.

Exclusion Criteria:

1. Current high risk of suicide or self-harm;
2. Severe cognitive impairment or neurocognitive difficulties that would prevent informed consent, completion of self-report assessments, or meaningful engagement with the self-guided online intervention.
3. Current severe psychiatric or medical condition that would make participation inappropriate or unsafe, or that would require more intensive clinical care than can be provided by a self-guided mental health promotion program.

De-identified individual participant data underlying the results reported in the published article may be made available upon reasonable request to the corresponding author, subject to approval by the study investigators.

Beginning after publication of the main study results.

Data will be made available to researchers who provide a methodologically sound proposal and whose proposed use of the data has been approved by the study investigators.