Placebo effect of acupuncture on insomnia: a systematic review and meta-analysis

Abstract

Background: Acupuncture is a common alternative therapy for clinical treatment of insomnia. As the underlying mechanism is yet unclear, its efficacy is often considered as placebo effect. To clarify whether acupuncture treatment of insomnia is only due to its placebo effect, a systematic review and a meta-analysis were designed based on the comparison between acupuncture and sham acupuncture.

Methods: Four English (PubMed, Embase, Web of Science, and The Cochrane Library) and three Chinese (CNKI, VIP, and Wanfang) databases were searched, and the validity of the eligible studies was critically appraised. Thirteen eligible randomized controlled trials of moderate-to-high quality that employed polysomnography (PSG), actigraphy, or self-assessment sleep quality tools were included in the present study. A meta-analysis was conducted using a random-effects model with the Pittsburgh Sleep Quality Index (PSQI) as the primary outcome measure (911 adult patients, 13 trials) for trials investigating the effects of acupuncture as compared to the sham acupuncture. Then, a subgroup analysis was performed to detect the sources of heterogeneity, identify the selection of sham acupuncture methods and different crowd characteristics, and explore its contributions to the total score change of PSQI.

Results: Compared to the sham groups, acupuncture significantly decreased the PSQI score (P<0.0001). A subgroup analysis showed that the selection of sham acupuncture methods did not affect the results of PSQI. A subgroup of two trials with a total of 141 participants with major depressive disorder did not show any significant reductions in total PSQI scores (P=0.11). In addition, a significant difference was detected in the change of Insomnia Severity Index (ISI) scores (362 adult patients, 4 trials) between acupuncture and sham acupuncture (P<0.0001). The PSG and actigraphy data from acupuncture and the sham did not reveal any significant differences in the sleep structure changes.

Conclusions: Acupuncture treatment of insomnia is efficacious, not because of its placebo effect. For the selection of sham acupuncture, both methods performed similarly in a clinical setting. Moreover, insomnia patients with major depression disorder were not recommended to use only acupuncture treatment.

Keywords: Acupuncture; insomnia; meta-analysis; placebo effect.