title: Hypnotherapy for insomnia: a systematic review and meta-analysis of randomized controlled trials.
abstract: OBJECTIVE
  To examine the efficacy and safety of hypnotherapy for insomnia as compared to placebo, pharmacological or non-pharmacological intervention, or no treatment.
  
  
  METHODS
  A systematic search on major electronic databases was conducted up until March 2014. Inclusion criteria are: (1) randomized controlled trials (RCTs) or quasi-RCTs; (2) intervention targeted at improving sleep; (3) hypnosis as an intervention; and (4) English language articles. Sleep diary variable is the primary outcome measure.
  
  
  RESULTS
  Six RCTs of hypnotherapy and seven on autogenic training or guided imagery, comprising 502 subjects, were included. Eleven of the 13 studies had low methodological quality, as indicated by a modified Jadad score below 3, and high risks of bias in blinding and design of the control interventions. No adverse events related to hypnosis were reported, though seldom investigated. Meta-analyses found hypnotherapy significantly shortened sleep latency compared to waitlist (standardized mean difference, SMD=-0.88, 95% confidence interval (CI): -1.56, -0.19, P=0.01, I(2)=15%), but no difference compared to sham intervention (SMD: -1.08, 95% CI: -3.15, 0.09, P=0.31, I(2)=90%). Similar results were found for autogenic training or guided imagery (SMD with waitlist=-1.16, 95% CI: -1.92, -0.40, P=0.003, I(2)=0%; SMD with sham intervention=-0.50, 95% CI: -1.19, 0.19, P=0.15, I(2)=0%).
  
  
  CONCLUSIONS
  Generalizability of the positive results is doubtful due to the relatively small sample size and methodological limitations. Future studies with larger sample size and better study design and methodology are called for.
authors.affiliation: Department of Psychiatry, University of Hong Kong, Hong Kong SAR, China.
authors.forename: Tak-Ho
authors.initials: TH
authors.lastname: Lam
authors.affiliation: Department of Psychiatry, University of Hong Kong, Hong Kong SAR, China. Electronic address: kfchung@hkucc.hku.hk.
authors.forename: Ka-Fai
authors.initials: KF
authors.lastname: Chung
authors.affiliation: Department of Psychiatry, University of Hong Kong, Hong Kong SAR, China.
authors.forename: Wing-Fai
authors.initials: WF
authors.lastname: Yeung
authors.affiliation: Department of Psychiatry, University of Hong Kong, Hong Kong SAR, China.
authors.forename: Branda Yee-Man
authors.initials: BY
authors.lastname: Yu
authors.affiliation: Department of Psychiatry, University of Hong Kong, Hong Kong SAR, China.
authors.forename: Kam-Ping
authors.initials: KP
authors.lastname: Yung
authors.affiliation: Department of Psychiatry, University of Hong Kong, Hong Kong SAR, China.
authors.forename: Tommy Ho-Yee
authors.initials: TH
authors.lastname: Ng
mesh_terms: D006801:Humans; D006990:Hypnosis; D016032:Randomized Controlled Trials as Topic; D007319:Sleep Initiation and Maintenance Disorders / Q000628:therapy*
keywords: Autogenic training; Guided hypnosis-like imagery; Hypnosis; Hypnotherapy; Hypnotic relaxation; Insomnia; Systematic review