Effectiveness of Guided Internet-delivered Cognitive Behavioral Therapy for Insomnia in Autistic Adults (i-Sleep Autism): a Randomized Controlled Trial

Abstract An estimated 60% of autistic adults suffer from insomnia symptoms, which significantly impairs daily functioning and wellbeing. This study evaluated the effectiveness of i-Sleep Autism, a 5-week, guided self-help internet-delivered cognitive behavioral therapy-based intervention (ICBT-I) for insomnia in autistic adults. In co-creation with seven autistic adults with sleeping problems, i-Sleep Autism was adapted from i-Sleep, a pre-existing non-autism specific intervention. A total of 163 adults with autism and insomnia (ISI≥10) was randomly allocated to i-Sleep Autism (n=82) or waitlist control (n=81; receiving psychoeducation and sleep hygiene). Participants were assessed at baseline (T0), mid-intervention (T1; 3-weeks), post-test (T2; 6-weeks), and follow-up (T3; 6 months) on insomnia severity (primary outcome), pre-sleep arousal, anxiety, depression, daily functioning, and quality of life. In the intervention group, 56.1% completed four, and 50% all five modules. Intent-To-Treat analyses revealed a significant reduction in insomnia severity at T1 and T2 (d = 1.02, 95%CI = [0.65, 1.40]), and cognitive- and somatic pre-sleep arousal at post-test, when comparing intervention to control. The intervention group showed significantly higher quality of life at post-test. At T2, 37.8% of the intervention group versus 11.1% of the control group showed clinically meaningful improvement of insomnia. Effects on insomnia severity were maintained at 6-month follow up. No significant effects were found for anxiety, depression, or daily functioning. This is the first RCT to investigate autism-adapted ICBT-I for autistic adults suffering from insomnia. i-Sleep Autism effectively and sustainably improves insomnia. Additional strategies are needed to support dropouts and those who did not benefit.