This randomized controlled trial will test the efficacy of CBT-I intervention for school-aged children (7-11 years old) with insomnia. The trial will focus on the role of sleep restriction therapy in treatment. Children will be randomized to one of three groups: (1) CBT-I; (2) CBT-I without SRT; or (3) a waitlist control group. Assessments will occur at baseline, mid-treatment, post-treatment, and a 3-month follow up. Some measures (e.g., child motivation) will also be assessed after each therapy session. Insomnia and sleep-wake patterns will be assessed objectively using actigraphy, and subjectively using sleep diaries, a clinical diagnostic interview, and questionnaires. Parent and child questionnaires will be administered to assess moderators and mediators of treatment outcomes.

Insomnia stands out as the most prevalent sleep disorder in youth, inflicting a range of adverse consequences on both the child and the family. While cognitive-behavioral therapy for insomnia (CBT-I) is considered the first-line treatment, empirical investigations into its efficacy in school-aged children have been scarce. Moreover, the unique contributions and underlying mechanisms of individual treatment components of the CBT-I 'package' remain poorly understood. Sleep Restriction Therapy (SRT) is acknowledged as a core module of CBT-I in adults, presumably driving clinical change via increases in homeostatic sleep pressure that facilitate sleep onset and maintenance. Yet, the incremental benefits of SRT within the context of CBT-I have not been systematically examined. Similarly, the role of two key mechanisms in the CBT-I 'package'-pre-sleep hyperarousal and parental over-accommodation-as mediators of treatment outcome has not been investigated. As for treatment moderators, the frequently encountered lack of motivation among children to engage in therapy poses a notable barrier to effective insomnia treatment, a barrier that SRT may potentially alleviate by offering the appeal of a later bedtime. Given the unique characteristics of insomnia in school-aged children and the prominent role played by parents in etiology and treatment, understanding these processes is pivotal. The proposed dismantling trial is designed to address these issues by rigorously testing the efficacy of CBT-I, including and excluding the SRT module, meticulously examining underlying mechanisms, and determining which variation of the intervention may be more suitable for specific children.

A total of 120 children aged 7-11 with chronic insomnia disorder will be randomized to one of 3 study arms: (1) CBT-I; (2) CBT-I without SRT; or (3) a waitlist control group. Assessments will occur at baseline, mid- treatment, post-treatment, and 3-month follow-up. Insomnia and sleep-wake patterns will be assessed objectively via actigraphy, complemented by parent and child questionnaires, sleep diaries, and a clinical diagnostic interview. Additional factors will be measured, including the child's presleep hyperarousal, separation anxiety, behavioral and emotional problems, as well as parental accommodation, distress and anxiety, and cry tolerance. Some of these factors will be tested as possible mediators (pre-sleep hyperarousal, parental accommodation, child motivation to engage in treatment, and family adherence to treatment) and moderators (parent and child levels of emotional or behavioral problems at baseline) of treatment outcome. Parents' satisfaction with treatment will also be assessed at post-treatment. Participants allocated to the waitlist control group will all receive CBT-I after the 5-week waiting period.

Inclusion Criteria:

• Child aged 7-11 years
• Parents aged over 18 years
• Child meets the International Classification of Sleep Disorders - Third Edition (ICSD-3) criteria for chronic insomnia disorder with sleep difficulties occurring at least 3 times a week and lasting at least 3 months (Insomnia diagnosis will be determined during a clinical interview).

Exclusion Criteria:

• Child receiving concurrent CBT treatment for sleep or anxiety disorders.
• Child diagnosed with a medical sleep problem (e.g., OSA, RLS)
• Significant health or neurodevelopmental problems (e.g., intellectual disability)
• Current psychotropic medications, or sleep aid medications
• Lack of Hebrew reading and writing
• Total sleep time that is shorter than 6 hours on average per night at baseline

We will share de-identified individual participant data upon reasonable request, including baseline demographic and clinical characteristics (e.g., age, gender, diagnosis, symptom severity at baseline), intervention assignment, and primary and secondary outcome measures. Data will be fully anonymized to protect participant confidentiality before sharing.

From June 2025 Until 7 years after study completion (anticipated December 2029)

Qualified researchers affiliated with academic or clinical institutions will be able to request access to the de-identified individual participant data (IPD) and supporting documentation. Requests for access will be reviewed on a case-by-case basis to ensure appropriate use and compliance with ethical and legal standards. Interested researchers can submit a data request to the corresponding author via email, including a brief proposal outlining the intended use and planned analyses. A data sharing agreement will be required prior to access. Data will be shared electronically via secure institutional file transfer systems.