Dismantling cognitive-behavioural therapy for chronic insomnia in adults with or without comorbidities: a systematic review and component network meta-analysis

Background: Chronic insomnia disorder is highly prevalent, disabling and costly. Cognitive-behavioural therapy for insomnia (CBT-I) is recommended as the first-line treatment. CBT-I may contain various educational, cognitive and behavioural strategies delivered in a range of formats, but the effect of each component remains unclear. Methods: We performed a systematic review and component network meta-analysis (cNMA) of CBT-I trials for chronic insomnia. We searched PubMed, CENTRAL, PsycINFO and ICTRP for randomised controlled trials published from database inception to 14th May 2022, comparing any form of CBT-I against each other or a control condition for chronic insomnia disorder in adults (aged ≥18 years). We included insomnia both with and without comorbidities. Concomitant treatments were allowed if they were equally distributed among the arms. Two independent reviewers identified components, extracted data, and assessed trial quality. Primary outcome of interest in this study was treatment efficacy (remission defined as reaching a satisfactory state at endpoint measured by any validated self-reported scale) at post‐treatment. (PROSPERO; CRD42022324233) Findings: We identified 226 trials, including 29,982 participants. Mean age was 45.7 years and 71% were women. The results suggests that critical components of CBT-I are cognitive restructuring (incremental odds ratio[iOR] 1.63 [95% confidence interval 1.25 to 2.14]), sleep restriction (iOR 1.44 [1.00 to 2.06]) and stimulus control (iOR 1.44 [1.00 to 2.07]) Sleep hygiene education was not essential (iOR 1.05 [0.79 to 1.38]) and relaxation procedures may be counterproductive (iOR 0.81 [0.64 to 1.03]). Face-to-face, therapist-led program was found to be most beneficial (iOR 1.86 [1.21to 2.85]). The overall risk of bias was low in 8% of the trials, some concerns in 56%, and high in 36%. Interpretation: This cNMA suggests that effective and efficient CBT-I packages can include cognitive restructuring, sleep restriction and stimulus control, but not relaxation. ### Competing Interest Statement YF has received consultancy fee from Panasonic outside the submitted work. MS reports personal fees from SONY outside the submitted work. SF received a research grant from JSPS KAKENHI (Grant Number JP 20K18964) and the Pfizer Health Research Foundation outside this project. EGO has received research and consultancy fees from Angelini Pharma. TAF reports personal fees from Boehringer-Ingelheim, DT Axis, Kyoto University Original, Shionogi and SONY, and a grant from Shionogi, outside the submitted work; In addition, TAF has patents 2020-548587 and 2022-082495 pending, and intellectual properties for Kokoro-app licensed to Mitsubishi-Tanabe. OE was supported by the Swiss National Science Foundation (Ambizione grant number 180083) MP wrote treatment manuals and books for CBT-I, teaches CBT-I, and is a founder of Hypknowledge LLC. RY, SN, SK, MIN, MIT, HN, HNT, OE report no competing interest. ### Clinical Protocols ### Funding Statement This study did not receive any funding ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors