The overall purpose with this investigation is to further our knowledge about cognitive behavioral therapy (CBT) for insomnia by examining treatment components, mediators, and moderators. The first aim that will be addressed is to explore the efficacy of the CBT components with a dismantling-treatment strategy. Two active CBT interventions, intended to define its components - cognitive therapy and behavior therapy - will be compared with one another as well as with a waitlist condition on a broad range of outcomes at five to nine assessment points depending on the measures. The design will thus enable us to examine what CBT component or components are necessary, sufficient and facilitative of therapeutic change. The second aim that will be explored is to investigate what processes occur in CBT that may contribute to treatment outcome with a treatment-mediator strategy. To examine mediators for CBT, the following mediators will be assessed; Anxiety and Preoccupation about sleep Questionnaire (APSQ), Dysfunctional Beliefs and Attitudes about Sleep (DBAS), Sleep Associated Monitoring Index (SAMI), Sleep-Related Behavior Questionnaire (SRBQ), time in bed, napping, bedtime variability, and rise time variability. The hypothesis is that cognitive processes will mediate cognitive therapy outcomes, and that behavioral factors will have a mediating role for behavior therapy improvements. The third aim that will be addressed is to examine what patient characteristics does CBT depend on to be effective with a treatment-moderator strategy. To investigate moderators for CBT, the following moderators will be assessed; age, gender, occupational status, level of education, initial insomnia severity, dysfunction, medication use, chronic pain, psychiatric co-morbidity, medical co-morbidity, behavioral and cognitive processes used as mediators will also be employed as moderators.

Inclusion Criteria:

• Presence of insomnia more than three nights per week and for more than three months.
• Insomnia despite adequate opportunity to sleep.
• Insomnia severity typical for insomnia disorder, i.e. 11 points or more on the Insomnia Severity Index (ISI).
• Nighttime insomnia symptoms, i.e., two points or more on at least one of the first three ISI questions.
• Daytime insomnia symptoms, i.e. two points or more on one or both of the ISI distress and impairment items (numbers 5 and 7).
• Clinical insomnia symptoms from sleep diaries concerning three nighttime symptoms (difficulties with sleep initiation, difficulties with sleep maintenance, and early morning awakenings), i.e., thirty minutes or more on average on one or more of the symptoms.
• No current or past CBT-I treatment within the past 5 years.
• Time and opportunity to participate in treatment for ten weeks.
• Time and opportunity to read approximately fifteen pages per week and execute homework assignments for ten weeks.
• Access to a computer, email and internet.

Exclusion Criteria:

• Severe depression, i.e., more than 30 points on MADRS-S.
• Suicidal risk, i.e., 4 points or more on item 9 on MADRS-S.
• A high intake of alcohol or caffeine,
• Insomnia due to shiftwork or other sleep-disturbing events (e.g., pregnancy, small children, or animals in the sleep environment).
• Participants with a history of psychotic or bipolar disorder.
• If a somatic condition is reported, it is required that it is relatively stable and/or that the candidate is receiving treatment for the condition.
• When a candidate fulfills criteria for a psychiatric or somatic condition, it is required that insomnia is the disorder currently most distressing and disabling or that the insomnia remains despite treatment for the comorbid condition.
• Participants with the following primary sleep disorders will be excluded via the Duke Structured Interview for Sleep Disorders (DSISD): sleep apnea, restless legs syndrome, periodic limb movement disorder, circadian rhythm disorder, and parasomnias.
• If sleep medication is used, it is required that the use has been relatively stable during three months.
• If Selective Serotonin Reuptake Inhibitors (SSRI) use is reported, it is required that the onset of the medication was at least three months prior to the telephone interview.
• Participants who regularly consume sleep-disturbing medications.