1 Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, Montreal, Quebec, Canada.
2 Concordia University, Department of Health, Kinesiology and Applied Physiology, Montreal, Quebec, Canada.
3 Concordia University, Center for Studies in Behavioral Neurobiology, Montreal, Quebec, Canada.
4 Concordia University, Department of Psychology, Montreal, Quebec, Canada.
5 Universite Laval, School of Psychology, Québec City, Quebec, Canada.
6 Université de Montréal, Département de Psychologie, Montreal, Quebec, Canada.

Insomnia and anxiety are highly prevalent and often comorbid in older adults. Although cognitive behavioural therapy is the first-line treatment for insomnia, few interventions simultaneously address both conditions. Furthermore, access remains limited by provider availability and high costs. To address these gaps, we developed an online CBT programme for insomnia and anxiety (eCBT+). This randomised controlled trial aimed to assess the usability and acceptability of the eCBT+ programme and evaluate its efficacy in older adults with insomnia. Eighty older adults with insomnia were randomised to the eCBT+ intervention (n = 38) or a waitlist (WL) control condition (n = 42). Platform usability and programme acceptability were assessed post-intervention using the System Usability Scale (SUS) questionnaire and the extended Technology Acceptance Model questionnaire. Insomnia and anxiety symptoms were evaluated with the Insomnia Severity Index (ISI) and Geriatric Anxiety Inventory (GAI) respectively, along with sleep-diary-derived sleep efficiency, at baseline and follow-up. Linear mixed models with an intention-to-treat approach assessed the Group*Time interaction. The platform was considered user-friendly (SUS = 69.94%). Perceived ease of use, perceived usefulness and result demonstrability were the main contributors to acceptability. The eCBT+ group showed reduced ISI and GAI and increased sleep efficiency, from baseline to follow-up, compared to the WL group (Ps < .001). The eCBT+ programme was user-friendly and its use was acceptable in older adults with insomnia. The programme improved sleep efficiency and reduced insomnia and anxiety symptoms, demonstrating the efficacy of our eCBT+ intervention. Web-based tools offer a promising approach to promote sleep and mental health among older adults (https://www.isrctn.com/ISRCTN15338211).