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.