A dysfunctional belief about sleep, like "Insomnia is damaging my capacity to enjoy life and prevents me from accomplishing what I want," may increase presleep distress and arousal and disrupt sleep by increasing presleep distress and arousal. In a review of 37 psychological studies conducted by Morin and colleagues, five CBT-I individual modules—stimulus control therapy, relaxation, paradoxic intention, sleep restriction, and cognitive-behavioral therapy— satisfied the criteria for scientifically supported treatments for insomnia. The most recent meta-analysis of 14 RCTs of CBT-I for primary insomnia found that impacts on sleep initiation and maintenance indices between the treatment and control groups (0.24-1.09) and within-subject effects (0.67-1.09) had medium to large mean effect sizes.

The primary objective of the cognitive therapy module is to cognitively restructure problematic, enduring sleep beliefs. Two approaches are frequently combined during the cognitive reorganization process. Identifying and implementing cognitive and/or behavioral measures to suppress dysfunctional sleep-related thoughts is one approach known as "thought-stopping." The second strategy, also known as "challenging automatic ideas," involves replacing undesirable automatic thoughts with alternative ones.