Group cognitive behavioural therapy for insomnia: Effects on sleep and depressive symptomatology in a sample with comorbidity.

Objective: To investigate the effects of group CBT for insomnia (CBT-I) on insomnia and depressive symptomatology in a comorbid sample through a randomised controlled trial with a 6 month follow-up.

Methods: 64 participants were recruited through advertisements and randomised to receive CBT-I or an active control (relaxation training: RT) during four group sessions. Insomnia Severity Index and BDI-II were the primary outcome measures, assessed pre-treatment, post-treatment and at 6 month follow-up. Insomnia and depressive diagnoses, and functional impairment were assessed before and after treatment, whereas sleep diary data was gathered continuously from one week before treatment until after treatment.

Results: CBT-I was more efficient than RT in reducing insomnia severity and equally effective in reducing depressive symptoms, although CBT-I was associated with a higher proportion of remitted persons than RT, regarding both insomnia and depression diagnoses. Also, CBT-I was associated with less functional impairment, shorter sleep onset latency and wake after sleep onset but both treatments had equal improvements of sleep quality, early morning awakenings and total sleep time.

Conclusions: Group CBT-I is an efficient form of insomnia-treatment for people with insomnia comorbid with depressive symptomatology. The mixed results regarding depression outcomes warrants replication and further studies into treatment mechanisms.