Randomised Evaluation of Sleep in Cognitive Impairment Trial (REST)-Protocol for a Feasibility Study of a Digital Cognitive Behavioural Therapy for Insomnia Intervention.

Dementia is a leading and growing cause of disability worldwide. Insomnia is highly prevalent in mild cognitive impairment (MCI) and dementia and is associated with impaired cognition, functional decline, and reduced quality of life (QoL). Although sleep disturbance represents a potentially modifiable risk factor within the trajectory of cognitive impairment, there have not been many studies conducted to examine the feasibility or preliminary efficacy of digital cognitive behavioural therapy for insomnia (dCBT-I) in this population. The aim of this pilot randomised controlled feasibility study is to evaluate the acceptability, adherence, and potential clinical effects of a multi-component dCBT-I programme (Sleepio) in adults with MCI or mild dementia and comorbid insomnia. Thirty community-dwelling adults aged ≥50 years with established MCI or mild dementia (Mini-Mental State Examination ≥18; Clinical Dementia Rating 0.5-1.0) and insomnia (Sleep Condition Indicator ≤16) will be randomised (1:1) to Sleepio or a wait-list control. Feasibility outcomes include recruitment and retention rates, intervention adherence (completion of ≥4/6 sessions), and acceptability measured using validated usability scales. Secondary outcomes include changes in sleep, mood, QoL, cognition, and function over 10 weeks. Adverse events will be monitored to assess safety. Findings will inform the design of a future definitive trial evaluating digital sleep interventions in cognitively impaired populations. Ethical approval has been granted. The trial is registered at ClinicalTrials.gov (NCT07363928).