Co-occurring insomnia and anxiety: a randomized controlled trial of internet cognitive behavioral therapy for insomnia versus internet cognitive behavioral therapy for anxiety

Insomnia and anxiety are highly prevalent and frequently co-occur. Given limited therapeutic resources and time constraints, the aim of this study was to compare which treatment-internet cognitive behavioral therapy (CBT) for insomnia or internet CBT for anxiety-leads to the best outcomes in individuals with comorbid insomnia and anxiety.120 participants with comorbid insomnia and clinical anxiety (as defined by scores above the clinical cutoff on the insomnia severity index (ISI) and the generalized anxiety disorder 7-item scale (GAD-7)) were randomized to receive internet-based cognitive behavioral therapy (iCBT) for insomnia or iCBT for anxiety. The primary outcome measures were the ISI and the generalized anxiety disorder 7-item scale. Primary outcome measures were assessed before treatment, at mid-treatment, at post-treatment, and 3 months after treatment. Secondary outcome measures assessed depression symptoms, distress, and sleep diary parameters.Participants in both groups experienced large reductions in symptoms of insomnia, anxiety, depression, and distress, as well as improvements in sleep efficiency and total sleep time. Improvements were maintained at follow-up. Crucially, at the end of treatment, the insomnia treatment was more effective in reducing symptoms of insomnia than the anxiety treatment, and equally effective in reducing symptoms of anxiety. Treatment gains were maintained at 3-month follow-up, however, there were no differences between groups at that time point.These results suggest that in the common case of a patient presenting with comorbid insomnia and anxiety, treatment for insomnia may be the most efficient treatment strategy.The trial was registered with the Australian and New Zealand Clinical Trials Registry, https://anzctr.org.au/Trial/Registration/TrialReview.aspx?ACTRN=12618001141235. Trial ID: ACTRN12618001141235. Trial name: a comparison of internet-based CBT for insomnia versus internet-based CBT for anxiety in a comorbid sample.