Usability, adherence and efficacy of coach-augmented dHealth cognitive behavioural therapy for insomnia in South African sexual assault survivors: a pilot study.

INTRODUCTION: Treating sleep difficulties - a core symptom of posttraumatic stress disorder (PTSD) - can improve both sleep and broader psychiatric outcomes. Digital health (dHealth) applications offer a scalable way to deliver cognitive behavioural therapy for insomnia (CBT-i), particularly for trauma survivors facing barriers to care. However, adherence to these interventions is often poor and may be improved through human support, especially for more demanding components such as sleep rescheduling. This study evaluated the usability, adherence, and preliminary efficacy of a dHealth application delivering sleep rescheduling both with and without coach support, alongside self-guided stimulus control and sleep hygiene components. METHODS: Female sexual assault survivors were assigned to one of two groups comparing the sleep rescheduling component of the dHealth application: either coach-assisted (n = 27) or self-guided (n = 27). All participants received stimulus control and sleep hygiene information embedded in the application, in the form of a newsletter, including a third comparator group (n = 25), which received this information only. Usability and negative effects were self-reported. Adherence was assessed via dropout rates, application engagement, newsletter openings, and compliance with sleep prescriptions. Efficacy was measured by changes in insomnia, depressive, and PTSD symptoms. RESULTS: The self-guided group reported lower satisfaction and more negative effects than controls. Compared to the self-guided group, coach-assisted participants showed better adherence to sleep prescriptions. Across groups, insomnia and depressive symptoms decreased significantly. Preliminary evaluation of efficacy showed that PTSD symptoms improved substantially in the coach-assisted and comparator groups, while improvements in the self-guided group plateaued after initial gains. DISCUSSION: Unguided application use was associated with poorer usability, greater negative effects, lower adherence, and some potential weaker outcomes. Preliminary findings suggest that sleep rescheduling may benefit from human support to be effective. Where coaching is unavailable, simple stimulus control and sleep hygiene education may be preferable.