Previous research has shown the efficacy of (combinations of) individual components of cognitive behavioral therapy for insomnia (CBT-I), namely sleep hygiene education, sleep optimization, stimulus control therapy, deactivation/relaxation training, and cognitive therapy. However, their relative effects, i.e., their effects in direct comparison with each other, are yet to be assessed.

In this pilot study, a smartphone and web application developed to treat insomnia using these treatment components will be tested.

Two future studies will investigate the components' relative efficacy in order to identify the most effective component or combination of components for digitized treatment of chronic insomnia by means of the Multiphase Optimization Strategy (MOST), and verify this intervention's effect in a randomized controlled trial (RCT).

As a pilot study for a Multiphase Optimization Strategy (MOST) study, the current study will assess the effects of a newly developed smartphone and web application for digitized cognitive behavioural therapy for insomnia (eCBT-I). All treatment components, i.e., sleep hygiene education, sleep optimization, stimulus control therapy, deactivation/relaxation training, and cognitive therapy, will be tested in order to receive feedback on the functioning of the application as well as to get an initial impression of possible treatment effects.

Inclusion Criteria:

• Adults (≥18 years)
• Individuals who report moderate-to-severe insomnia symptoms (a score ≥10 on the Insomnia Severity Index, ISI)
• Individuals with access to a smartphone or computer with internet connection
• Individuals who report sufficient technological proficiency (e.g., ability to download apps)

Exclusion Criteria:

• Children (<18 years)
• Individuals who report mild or no clinically relevant insomnia symptoms (a score <10 on the ISI)
• Individuals who have a shift-work schedule or are on maternity/paternity leave, if this impacts their sleep quality or amount of sleep
• Individuals who are unable to read Danish
• Individuals who report severe physical or psychological comorbidity with known effects on sleep (e.g., psychosis, cardiovascular disease, cancer, COPD)
• Individuals who report other diagnosed sleep or circadian rhythm disorders (e.g., sleep apnea, narcolepsy)
• Individuals who have previously used the "Hvil®"-app, e.g., during the beta test phase

All individual participant data collected during the study will be made available in an irreversibly anonymized form. However, only data of those participants can be shared who have explicitly given consent to this as part of their informed consent to study participation. This means that it may not be possible to share all data underlying a certain publication.

Data will be shared exclusively for research purposes.

No later than six months after publication, no end date.

Data will be shared exclusively with other researchers and for research purposes only. Researchers requesting the data will have to provide a methodologically sound research proposal clarifying how the data will be used and for what purpose.