Study objectives: Hypnotherapy is commonly used for treating insomnia, but a definite conclusion regarding its safety and effectiveness is unavailable due to a lack of adverse event monitoring and comparison between generic and disease-specific hypnotic suggestions in previous studies.
Design: Randomized controlled, participant-blind, parallel-group with subject recruitment after trial registry.
Interventions: Sixty participants were randomized to receive 4-week once-weekly 1-hour hypnotherapy with disease-specific suggestions (using counter-hyperarousal hypnotic exercise and screen visualization technique targeted at insomnia-related anxieties) or generic suggestions (using thought distraction technique and suggestions for self-confidence and self-care enhancement).
Main outcome measures: Primary outcome was sleep efficiency (SE) derived from 1-week sleep diary at weeks 4, 6 and 9. Secondary outcomes included other sleep-diary parameters, Insomnia Severity Index, Hospital Anxiety and Depression Scale, and Sheehan Disability Index. Treatment expectancy, adverse events (AEs), and subjective experiences were obtained after hypnotherapy sessions 2 and 4.
Results: Mixed linear modeling showed that time effect was significant for most variables. Within-group effect size of sleep-diary-derived SE from baseline to follow-up ranged from 0.70 to 0.90 for disease-specific suggestions (mean difference: 8.5-10.4%); for generic suggestions, it was 0.65-0.69 (mean difference: 6.8-8.3%); however, no significant between-group difference was found. Discontinuation rate was 10%, report of unpleasantness varied from 5.5 to 7.4%, while the incidence of AEs ranged from 37.0 to 51.8%, depending on session content.
Conclusion: Hypnotherapy using disease-specific and generic suggestions produced similar improvements in sleep and daytime functioning. AEs were common but mostly mild. The finding raises doubts about the value of disease-specific suggestions in hypnotherapy for insomnia.
Trial registration: This clinical trial was registered on 23 May 2014 at the University of Hong Kong Clinical Trials Registry as "Hypnotherapy for insomnia: a randomized placebo-controlled trial" (HKUCTR-1874).
Keywords: Disease-specific suggestions; Generic suggestions; Hypnosis; Hypnotherapy; Insomnia; Randomized controlled trial; Sleep.
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