Background: In view of the high co-occurrence of depression and insomnia, a novel way to reduce the risk of escalating depression might be to offer an insomnia intervention. We aimed to assess whether an online self-help insomnia program could reduce depression symptoms.
Methods: We did this randomised controlled trial at the Australian National University in Canberra, Australia. Internet users (aged 18-64 years) with insomnia and depression symptoms, but who did not meet criteria for major depressive disorder, were randomly assigned (1:1), via computer-generated randomisation, to receive SHUTi, a 6 week, modular, online insomnia program based on cognitive behavioural therapy for insomnia, or HealthWatch, an interactive, attention-matched, internet-based placebo control program. Randomisation was stratified by age and sex. Telephone-based interviewers, statisticians, and chief investigators were masked to group allocation. The primary outcome was depression symptoms at 6 months, as measured with the Patient Health Questionnaire (PHQ-9). The primary analysis was by intention to treat. This trial is registered with the Australian New Zealand Clinical Trials Registry, number ACTRN12611000121965.
Findings: Between April 30, 2013, and June 9, 2014, we randomly assigned 1149 participants to receive SHUTi (n=574) or HealthWatch (n=575), of whom 581 (51%) participants completed the study program assessments at 6 weeks and 504 (44%) participants completed 6 months' follow-up. SHUTi significantly lowered depression symptoms on the PHQ-9 at 6 weeks and 6 months compared with HealthWatch (F[degrees of freedom 2,640·1]=37·2, p<0·0001). Major depressive disorder was diagnosed in 22 (4%) participants at 6 months (n=9 in the SHUTi group and n=13 in the HealthWatch group), with no superior effect of SHUTi versus HealthWatch (Fisher's exact test=0·52; p=0·32). No adverse events were reported.
Interpretation: Online cognitive behaviour therapy for insomnia treatment is a practical and effective way to reduce depression symptoms and could be capable of reducing depression at the population level by use of a fully automatised system with the potential for wide dissemination.
Funding: Australian National Health and Medical Research Council.
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