Attribution, cognition and psychopathology in persistent Insomnia Disorder: outcome and mediation analysis from a randomized placebo-controlled trial of online cognitive behavioral therapy

Objectives: Insomnia patients complain that mental events keep them awake. This study investigates how cognitive behavioral therapy (CBT) affects such events, and considers how attributional, cognitive, and psychpathological symptoms may mediate sleep improvement.<p></p> Method: Pragmatic, parallel group randomized controlled trial of 164 adults (120 F: [mean 49y (18–78y)] meeting DSM-5 criteria for Insomnia Disorder, assigned to CBT (n=55; 40F), Imagery Relief Therapy (IRT placebo; n=55; 42F) or Treatment as Usual (TAU; n=54; 38F). CBT/IRT comprised 6 online sessions delivered by an animated therapist, with automated web/email support. CBT users had access to a moderated community. TAU comprised ‘usual care’. Participants completed the Sleep Disturbance Questionnaire (SDQ), Glasgow Content of Thoughts Inventory (GCTI), Depression Anxiety and Stress Scales (DASS) and Sleep Condition Indicator (SCI) at baseline, post-treatment and 8 weeks follow-up.<p></p> Results: The sample was characterised by mental arousal, notably ‘trying too hard’ to sleep (SDQ), and by ‘sleep and sleeplessness’ and ‘rehearsal and planning’ thoughts (GCTI). Treatment effects were observed for all SDQ domains (e.g. CBT v. IRT: d=.76 for ‘trying too hard’). CBT was also superior to IRT on the GCTI (e.g. ‘rehearsal and planning’, d=.62; ‘sleep and sleeplessness’, d=.74). CBT v. TAU comparisons yielded larger effects whereas placebo effects (IRT v. TAU) were small to moderate. Hierarchical regression demonstrated partial mediation of SCI improvement by attributional and cognitive factors (R2 =21-27%) following CBT. Improvement in Sleep Efficiency appears to be independent of such factors.<p></p> Conclusion: Online CBT modifies sleep-related attributions, night-time thought content and psychopathology. This process partly mediates improvement in DSM-5 defined insomnia