Around 85% of people with depression also struggle with chronic insomnia, and this trial tests whether fixing the sleep problem can directly improve the depression itself. The problem is that standard depression treatments—antidepressants and talking therapies—fail for a significant minority of patients. Insomnia is not just a symptom of depression; mounting evidence suggests it helps cause and maintain the condition. Targeting sleep could open a new treatment pathway without requiring new drugs or lengthy psychological therapy. The trial will recruit 250 adults with both major depression and insomnia from 13 GP practices in Thames Valley. Half will continue their usual depression care; the other half will also receive six sessions of sleep restriction therapy delivered by a nurse—a structured programme that limits time in bed to rebuild healthy sleep patterns. The primary outcome is depression severity six months later. If sleep restriction therapy reduces depression, it would offer a practical, low-cost addition to primary care—something a practice nurse can deliver, requiring no specialist mental health training. The trial also tracks whether sleep improvement changes how the brain processes negative emotions, which could reveal the mechanism linking sleep and mood.
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Background: Depression is a highly prevalent and impairing condition. Effective treatments exist but a significant minority of patients do not respond to pharmacotherapy or psychological therapy; there is a clear need for innovation with a focus on novel targets. Insomnia characterises 85% of patients with depression. Mounting clinical and experimental evidence suggests that insomnia is involved in both the causation and perpetuation of depression. Aims and objectives: Our primary objective is to test if adding an effective behavioural sleep intervention to existing depression care improves depression outcomes. Our secondary objectives are to assess whether the intervention improves depression via change in insomnia symptoms, and to assess whether the intervention drives change in mechanistic processes presumed to underlie the causal association between insomnia and depression. Design: Individually randomised, parallel group, explanatory clinical trial design to compare sleep restriction therapy (SRT+treatment as usual; TAU) with TAU on its own. Participants will be randomised to SRT+TAU (135 participants) or TAU (115 participants) using a validated web-based randomisation programme. Setting: Participants will be recruited through 13 general practices in Thames Valley. Target population: Adults aged 18 yrs and over who meet criteria for major depression and insomnia. Interventions/control: All participants in the trial will continue to receive TAU. In addition, the SRT arm will receive six nurse-delivered treatment sessions (three in-person at the practice and three over the phone). Participants will be supported by the nurse to implement a new sleep schedule according to weekly review of their sleep pattern. Outcomes: We will collect outcomes at baseline, 4, 8, and 26 weeks post-randomisation. The primary outcome is depression severity at 26 weeks measured with the PHQ-9. Insomnia severity (measured with the ISI at 4 weeks) is the mediator of interest. Mechanistic outcomes include objective sleep and circadian rest-activity rhythms (actigraphy), negative emotion processing bias (Oxford Emotional Test Battery), affect (Positive and Negative Affect Schedule) and repetitive negative thinking (Perseverative Thinking Questionnaire). Sample size and analysis: Assuming a minimum between-group standardised effect size difference of 0.50, with power set at 90%, significance level at 5%, and accounting for up to 20% attrition, a sample size of 250 participants (135 participants in the SRT + TAU group, 115 participants in the TAU only group) is required to detect effects on the primary depression outcome at 26 weeks. The sample size also accounts for the “therapist effect”, assuming an intraclass correlation coefficient of 0.01 and a cluster size of 40. The primary analysis will be according to randomised group and will use a linear mixed model to estimate treatment differences in depression severity at 26 weeks, adjusting for minimisation factors. Timetable: Prior to funded period=recruit team, finalise protocol, submit to ethics; M1-M6=trial set-up and nurse training; M7-M22=recruitment period (including 4 month internal pilot), randomising ~20 patients per month; M23-M30=complete follow-up; M31-M36=trial close-out, analysis, and final report. Anticipated impact and dissemination: Results have the potential to 1) identify a new pathway to treating depression (through insomnia reduction); and 2) elucidate mechanisms linking sleep improvement and mental health. We will work with our PPI advisory group, University media office, and partner charity (Mental Health Foundation) to disseminate trial findings through social media and seminar events.
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