Process evaluation in a randomised controlled trial of DREAMS-START (dementia related manual for sleep; strategies for relatives) for sleep disturbance in people with dementia and their carers.

Introduction: DREAMS-START is a multicomponent intervention targeting sleep disturbance in people with dementia. To enhance understanding of the DREAMS-START randomised controlled trial, which showed improved sleep in the intervention compared to the control arm, we conducted a process evaluation exploring (i) DREAMS-START delivery, (ii) behaviour change mechanisms and (iii) contextual factors impacting outcomes.

Methods: Mixed-methods design. We measured intervention adherence, fidelity and additional therapeutic process measures. We interviewed a sub-sample of intervention arm family carers and facilitators delivering DREAMS-START. We analysed data thematically guided by a prespecified theory of change logic model informed by the Theoretical Domains Framework. We measured movement using an actigraph worn by the person with dementia at baseline and at four- and eight-month follow-ups to explore potential mechanisms of action.

Results: Attendance was good (82.8% attended ≥4/6 sessions). Mean fidelity score (95.4%; SD 0.08) and median score for all four process measures assessed (5/5; IQR 5-5) were high. We interviewed 43/188 family carers and 9/49 DREAMS-START facilitators. We identified three overarching themes aligned with our model: (i) knowledge and facilitation enable behaviour change, (ii) increasing sleep pressure and developing skills to manage sleep disturbances and (iii) Establishing a routine and sense of control. We were unable to collect sufficient data for pre-specified actigraphy analyses.

Conclusion: Despite competing demands, carers attended DREAMS-START. It promoted behaviour change through supportive in-session reflection, increasing carer knowledge and skills. This was embedded between sessions and actions were positively reinforced as carers experienced changes. Results will inform future implementation in clinical services.