The Sleep Course: Examining the feasibility, acceptability, and outcomes of an online sleep intervention for adults with self-reported sleep difficulties

Insomnia is linked to significant impairments in daily functioning and commonly co-occurs with depression and anxiety. Internet-delivered cognitive behavioral therapy for insomnia (ICBT-i) is a well-established first-line treatment for sleep difficulties. However, its utility in routine care settings remains underexplored, as most evidence comes from trials conducted in highly selected samples. This study examined feasibility, acceptability, and outcomes of a seven-week ICBT-i intervention among 95 adults (78% women, mean age 52 years, SD = 15) with self-reported sleep difficulties delivered in a routine care ICBT clinic. Insomnia severity, sleep quality, dysfunctional beliefs and attitudes about sleep, anxiety symptoms, and depressive symptoms were assessed at pre-treatment, post-treatment, and three-month follow-up. Results demonstrated significant and large long-term improvements in insomnia severity ( d = 1.43) and sleep attitudes ( d = 1.09), as well as small to large improvements in most of the sleep quality parameters ( d = 0.33–0.96), and associated symptoms ( d = 0.34–0.60). The intervention also showed high rates of satisfaction (88%) and lesson completion (73%). These findings support the feasibility, acceptability, and utility of ICBT-i as a scalable intervention for adults with sleep difficulties in routine care settings.