Study Objectives: Our aim was to compare the effects of Internet-delivered cognitive therapy (CT) and behavior therapy (BT) against a waitlist (WL) condition to better understand their unique contribution in the treatment of insomnia.

Methods: Two hundred and nineteen participants with insomnia disorder were randomized to CT (n = 72), BT (n = 73), or WL (n = 74). The treatment arms consisted of 10 weekly internet-delivered modules with 15 min of telephone support per week. At pre, post, and follow-up, participants completed measures of insomnia severity, sleep diaries, functional impairment, anxiety, depression, quality of life, adverse events, satisfaction and perception of content, workload, and activity in treatment. Measures of completed exercises, modules, therapist support, and platform logins were also measured at posttreatment.

Results: Moderate to large effect sizes for both CT and BT outperformed the WL on the majority of outcomes, with significant differences in favor of both therapy groups. Both treatment groups had significantly larger proportion of treatment remitters (CT: 35.8%, BT: 40%, WL: 2.7%) and responders (CT: 74.6%, BT 58.6%, WL: 10.8%) compared to the WL at posttreatment. There were no significant differences between the two therapy groups in terms of outcomes, except for sleep onset latency in favor of BT (6 min difference at posttreatment) and adverse events in favor of CT (CT 14.1% vs BT 43.2%).

Conclusions: This study indicates that both Internet-delivered CT and BT are effective as stand-alone therapies for insomnia disorder. Results highlight the need for examining which therapy and subcomponents that are necessary for change.

ClinicalTrials.gov Identifier: NCT02984670

Objective: To examine if the processes in the cognitive model mediate cognitive therapy (CT) and behavior therapy (BT) for insomnia.

Method: Individuals diagnosed insomnia disorder (n=219) were randomized to telephone supported internet-delivered cognitive therapy (n=72), behavior therapy (n=73), or a waitlist (n=74). Cognitive processes (worry, dysfunctional beliefs, monitoring and safety behaviors) proposed to maintain insomnia and treatment outcome (insomnia severity; ISI) were assessed biweekly. Criteria for evaluating mediators were assessed via parallel process growth modeling and cross-lagged panel models.

Results: Parallel process growth modeling showed that dysfunctional beliefs, monitoring and safety behaviors significantly mediated the effects of both CT and BT. Cross-lagged panel models confirmed that dysfunctional beliefs and monitoring, which approached significance, drove the change for CT. In BT, however, prior changes in ISI predicted later changes in worry and monitoring, and reciprocal influences among processes and outcomes were observed for dysfunctional beliefs and safety behaviors. The effect of safety behavior on outcome was significantly larger for BT compared to CT.

Conclusion: Together, the findings support the role of dysfunctional beliefs and monitoring as processes of change in CT, and safety behaviors as a specific mediator in BT. Limited evidence was provided for worry as a mediator. These findings have relevance for the conceptualizations of insomnia, future research, and clinical management.