The primary objective of this study is to test the feasibility and efficacy of Internet-delivered Cognitive Behavioral Therapy (CBT) for adolescents (13 - 17 years) with sleep problems (ICBT-I). All participants will receive ICBT-I for six weeks. The investigators will also evaluate the effect of the intervention on comorbid psychiatric symptoms and function.

PARTICIPANT RECRUITMENT:

For recruitment, this pilot trial will be advertised at child and adolescent mental health services and primary care clinics, as well as through newspapers. The inclusion procedure will be carried out in two steps: 1) telephone interview and 2) face-to-face assessment.

Telephone interview: An initial telephone interview will be conducted with the adolescent/parent in order to broadly assess inclusion and exclusion criteria.

Face-to-face baseline diagnostic assessment: After the telephone screening, the adolescent along with his/her parents, are invited to a face-to-face assessment at the Child and Adolescent Mental Health clinic, including the diagnostic screening interview MINI-KID conducted with adolescents and parents jointly. Insomnia diagnoses will be established using DSM-IV criteria and levels of insomnia symptoms will be determined using ISI-a. If the ISI-a score is >10, the family will be invited to participate in the study, provided that the other inclusion criteria are fulfilled and no exclusion criteria prohibit participation. Following face-to-face assessment, participants will be provided with an information sheet and consent form.

DATA COLLECTION:

Baseline self-report measures: Participants included in the study after the face-to-face diagnostic assessment are asked to fill in self-report measures on the internet, provided via personal login and password. Participants will aslo be asked to fill in a sleep-wake diary and to wear an actigraph during seven consecutive days/nights.

Self-rating assessments during intervention: ISI-a is administered to adolescents every week during treatment.

Study participants are in regular contact (on a weekly basis) with experienced clinicians during the ICBT-I treatment. Clinicians that suspect any kind of adverse event during the assessment or treatment process will contact the parent via telephone as a first step of assessing the severity of the incident. Adverse events in this context are defined as an actual or potential situation that threatens the patient's well-being, e.g., suicide risk or an acute increase of symptoms. In the case of an adverse event, the clinician informs the study coordinator (LÅ) for a discussion of adequate action taking. If a continuation of the ICBT treatment is considered inappropriate with regard to the participants' best interest and well-being, the participant will be excluded from the study and parents/adolescents will be provided with proper referral information. Any adverse event will be reported in the planned publication of the pilot study.

Outcome measure reliability procedures: To ensure the reliability of the assessments conducted by study clinicians, all assessors will be trained by experienced instructors in the diagnostic screening instrument MINI-KID. All therapists that participate in the study will also be continuously trained in MINI-KID interviewing, assessment and diagnosing.

Post-treatment and follow-up measurement: Post-treatment measurement with actigraphy, sleep-wake diary and self-report measures will be conducted immediately after treatment (6 weeks after baseline). A follow-up measurement will be performed 6 months after treatment termination.

Referral of non-responders After the 6-month follow-up, all non-responders (defined as those participants who have not improved to a clinically meaningful degree according to ISI-a) will be referred to their local child-and adolescent psychiatric clinic for further treatment.

Statistical Analyses Outcomes will be described as significant changes in objective and subjective sleep and in clinician and self-rated measures of insomnia symptoms and comorbid symptoms, within-group effect sizes (Cohen's d), clinically significant improvement rates and remission rates. Analyses will involve t-tests as well as linear mixed-effects modeling. Randomness of missing data will be analyzed with logistic regression. Depending on the amount of missing data, multiple imputations will be employed to compensate for missing values.

Inclusion Criteria:

• Clinical levels of insomnia symptoms, as determined by ISI-a >10.
• Age between 13 and 17 years
• Ability to read and write Swedish
• Daily access to the internet through a computer or similar device
• Participants on psychotropic medication must have been on a stable dose for the last 6 weeks prior to baseline assessment

Exclusion Criteria:

• Diagnosed with autism spectrum disorder, psychosis or bipolar disorder
• Present risk of suicide
• Ongoing substance dependence
• Completed CBT for sleep disorders within the last 6 months (defined as at least 5 sessions of CBT
• Ongoing use of central nervous system stimulant medication