Transdiagnostic Sleep Intervention to Improve Mental Health in Adolescents

Background. Adolescence is a period of heightened vulnerability to mental health problems, and insufficient or poor-quality sleep is highly prevalent in this age group. Sleep disturbance is associated with both internalizing (e.g., depression, anxiety) and externalizing problems (e.g., substance use) and is considered a transdiagnostic factor. TranS-C (Harvey \& Buysse, 2018) is a cognitive-behavioral intervention that targets a broad range of sleep and circadian problems from a common framework. However, school-based preventive sleep interventions remain scarce, and none has been evaluated in Spain.

Design. Two-arm, parallel-group, cluster randomized controlled trial with a pre-post design and 3-, 6- and 9-month follow-ups. The unit of randomization is the school. Public secondary schools in Navarre, including both Spanish- and Basque-language schools, will be stratified by location (urban vs. rural). Schools will be computer-randomized within strata in a 1:1 ratio to TranS-C or control. Reserve schools will be randomized in advance to replace schools that decline or withdraw. One reserve school will host a pilot implementation before the main trial to refine the adapted protocol.

Interventions. TranS-C will be adapted to a group, school-based format for Spanish adolescents in collaboration with its developer (Dr. Allison Harvey, University of California, Berkeley). The adaptation includes translation and cultural adaptation of materials. The control condition is a healthy-habits psychoeducation program (nutrition, physical activity, appropriate social media use, hygiene) matched in number and duration of sessions. Both programs are delivered in school hours by psychologists trained in both protocols.

Assessments. Self-report questionnaires are administered online in group sessions at school (baseline and post-intervention) and online at follow-ups. Questionnaire order is counterbalanced. Participants are identified by an anonymous code to link assessments.

Statistical analysis. Intervention effects over time will be estimated with generalized linear mixed models (GLMMs). These models include random intercepts and slopes to account for the nesting of repeated measures within participants and of participants within schools, and they adjust for sex, age, socioeconomic status, school location and the delivering psychologist. Analyses will follow the intention-to-treat principle. Missing data will be handled by multiple imputation. Exploratory mediation analyses will examine whether changes in sleep mediate changes in psychological symptoms. The significance level is set at α = .05.

• Transdiagnostic Intervention for Sleep and Circadian Dysfunction (Behavioral): It combines cognitive-behavioral techniques, sleep medicine principles and circadian regulation strategies to establish regular sleep-wake schedules and modify dysfunctional sleep-related beliefs and behaviors. It consists of four weekly 45-minute sessions delivered in school hours by trained psychologists.
• Healthy habits psychoeducation (Behavioral): Attention-control program covering healthy nutrition, physical activity, and hygiene habits. It consists of four weekly 45-minute group sessions delivered in school hours by trained psychologists.

Primary outcomes

• Change from baseline in Sleep Quality assessed by the Brief Pittsburgh Sleep Quality Index (B-PSQI) Global Score and its dimensions. [Baseline, post-intervention (week 4), and 3, 6 and 9 months post-intervention]: Sleep quality over the past month is measured with the 6-item adolescent Spanish version of the B-PSQI. It assesses sleep duration, sleep latency, night awakenings, sleep efficiency, sleep schedule and subjective sleep quality. The global score ranges from 0 to 15, with higher scores indicating worse sleep quality.

Secondary outcomes

• Change from baseline in Depressive Symptoms as Assessed by the SA-45 Depression Subscale Score and the DASS subscale for depression [Baseline, post-intervention (week 4), and 3, 6 and 9 months post-intervention]: The SA-45 is a 45-item short form of the Symptom Checklist-90. Items are rated from 0 (not at all) to 4 (very much) for the past week. The depression subscale has 5 items, and its score ranges from 0 to 20. Higher scores indicate more severe symptoms. The DASS-21 depression subscale has 7 items assessing symptoms over the past week. Each item is rated from 0 (did not apply to me at all) to 3 (applied to me very much or most of the time). The subscale score is the sum of the items multiplied by 2, giving a range from 0 to 42. Higher scores indicate more severe depressive symptoms.
• Change From Baseline in Anxiety Symptoms as Assessed by the SA-45 Anxiety Subscale Score and the Depression Anxiety Stress Scales-21 (DASS-21) Anxiety Subscale Score [Baseline, post-intervention (week 4), and 3, 6 and 9 months post-intervention]: The SA-45 is a 45-item short form of the Symptom Checklist-90. Items are rated from 0 (not at all) to 4 (very much) for the past week. The Anxiety subscale has 5 items, and its score ranges from 0 to 20. Higher scores indicate more severe symptoms. The DASS-21 Anxiety subscale has 7 items assessing symptoms over the past week. Each item is rated from 0 (did not apply to me at all) to 3 (applied to me very much or most of the time). The subscale score is the sum of the items multiplied by 2, giving a range from 0 to 42. Higher scores indicate more severe anxiety symptoms.
• Change From Baseline in Number of Standard Drinks Consumed in the Past 30 Days as Assessed by the Timeline Follow-Back (TLFB). And Number of Participants Reporting Drug Use as Assessed by the Drug Use History Questionnaire (DUHQ) [Baseline, post-intervention (week 4), and 3, 6 and 9 months post-intervention]: The TLFB is a retrospective calendar method for recording daily alcohol consumption over the past 30 days. One standard drink unit equals 10 g of alcohol. Higher values indicate greater alcohol use. The DUHQ, adapted for adolescents, assesses use of 11 substance classes. This outcome is the number of different substance classes used in the past year, ranging from 0 to 11. Higher values indicate more substances used.
• Change From Baseline in Impulsivity as Assessed by the Barratt Impulsiveness Scale-Brief (BIS-Brief) Total Score [Baseline, post-intervention (week 4), and 3, 6 and 9 months post-intervention]: The BIS-Brief has 8 items rated on a Likert scale. The total score ranges from 8 to 32, with higher scores indicating greater impulsivity.
• Change From Baseline in Reward Responsiveness as Assessed by the BIS/BAS Scales Reward Responsiveness Subscale Score [Baseline, post-intervention (week 4), and 3, 6 and 9 months post-intervention]: The Reward Responsiveness subscale of the BIS/BAS Scales (Carver \& White, 1994) has 5 items, each rated from 1 (very false for me) to 4 (very true for me). The score ranges from 5 to 20, with higher scores indicating greater reward responsiveness.

Other outcomes

• Change From Baseline in Interpersonal Dysfunction as Assessed by the SA-45 Interpersonal Sensitivity Subscale Score [Baseline, post-intervention (week 4), and 3, 6 and 9 months post-intervention]: This 5-item SA-45 subscale is rated from 0 to 4. The score ranges from 0 to 20, with higher scores indicating greater interpersonal dysfunction.

Sex: All, ages: 13 Years to 17 Years, accepts healthy volunteers

Inclusion Criteria:

* Aged 14 to 17 years
* Enrolled in compulsory secondary education (ESO), upper secondary (Bachillerato) or vocational training (FP) in a participating public school in Navarre, Spain
* Written informed consent from the participant and their legal guardian(s)
* Valid self-report responses (≥75% correct answers)

Exclusion Criteria:

* Comprehension difficulties that prevent participation (e.g., language disorders)
* Severe physical or mental health problems that prevent participation in the program
* Currently receiving pharmacological or psychological treatment for sleep problems