A protocol for a mixed-methods analysis of the usability and acceptability of a digital cognitive-behavioural therapy for insomnia (dCBT-I) intervention ( Sleepio TM) in participants with cognitive impairment.

Background: Sleep disturbance is common among those with cognitive impairment, potentially contributing to negative outcomes. Furthermore, growing evidence suggests that sleep disturbance is associated with the onset and progression of cognitive decline. There is therefore increasing interest in treating sleep disturbance in people with cognitive impairment.Non-pharmacological treatments for sleep disturbance are unhindered by many of the adverse effects associated with pharmacological treatments, yet evidence supporting their use in clinical practice is often lacking. Cognitive behavioural therapy for insomnia (CBT-I) is the first-line treatment for insomnia and has demonstrated effectiveness in people with cognitive impairment in a small number of trials. Digital CBT-I (dCBT-I) overcomes many of the obstacles associated with accessing CBT-I (such as limited availability of therapists and transportation) whilst presenting others (such as internet access and digital literacy). Aim: To undertake a mixed-methods analysis of the usability and acceptability of a dCBT-I intervention ( Sleepio) among people with cognitive impairment. Methods: Participants will be community-dwelling adults aged ≥50 years with cognitive decline and probable insomnia. Study partners (being caregivers, family or friends of participants) will be recruited, if available, to examine how their involvement influences usability and acceptability.Participants will be given access to Sleepio, a fully automated and personalised dCBT-I programme delivered over the course of six weekly sessions. Usability and acceptability will be assessed by a bespoke questionnaire incorporating the System Usability Scale and the Usability Metric for User Experience - Lite (UMUX-Lite). Semi-structured interviews will explore participants' experience of using the intervention. Conclusion: By examining barriers and facilitators to the usability and acceptability of Sleepio among people with cognitive impairment, this study will provide insight into the potential efficacy of the intervention in this population whilst informing the design of a future definitive clinical trial.