Effectiveness of cognitive behavioral therapy for insomnia: influence of slight-to-moderate depressive symptom severity and worrying.

Background: Cognitive behavioral therapy for insomnia (CBT-I) is a well-known, effective treatment for primary insomnia. However, the majority of sleeping problems occur in the presence of another medical or psychiatric disorder. Depression and general anxiety disorder (with a main feature of excessive generalized worrying) are disorders that frequently co-occur with insomnia. The purpose of this study is to evaluate whether depressive symptom severity or worrying influences the subjective effectiveness of CBT-I.

Methods: Patients with a complaint of insomnia received CBT-I. At the beginning of the therapy, patients completed a sleep evaluation list, the Beck Depression Inventory (BDI-II-NL, N = 92), and the Penn State Worry Questionnaire (PSWQ, N = 119). Based on the BDI and the PSWQ, the sample was divided into different groups: patients with low versus high depression scores, low worriers versus high worriers, and patients without depressive symptoms who were also classified as low worriers and patients with depressive symptoms who were also classified as high worriers. The sleep evaluation list was completed directly after the treatment and 6 months later.

Results: Sleep evaluation scores, subjective total sleep time, subjective sleep onset latency, and subjective wake after sleep onset all changed in a positive way after CBT-I and remained that way over the next 6 months for all patients. These positive effects of CBT-I did not differ between the subgroups.

Conclusions: Results suggest that CBT-I improves subjective sleep experiences, regardless of depressive symptom severity or worrying.