Can acupuncture improve objective sleep indices in patients with primary insomnia? A systematic review and meta-analysis

Background: The efficacy of acupuncture for treating primary insomnia (PI) has been explored in several meta-analyses where the outcomes measures were based on subjective self-reported sleep rating scales. Sleep state misperception is common in PI and self-reports underestimate sleep duration and quality. No systematic reviews or meta-analyses have investigated the efficacy of acupuncture in improving objective sleep measures in PI. Objective: To perform a systematic review to determine whether objective sleep parameters are improved by acupuncture in patients with PI. Methods: Randomized controlled trials treating PI via verum-acupuncture versus sham-/placebo-acupuncture or waitlist control were searched for in English [MEDLINE (via PubMed), Sciverse ScienceDirect, Cochrane Central Register of Controlled Trials (CENTRAL), AMED, Springer, EMBASE (Elsevier), Ebsco Medline, and PsycINFO (ProQuest)] and Chinese (SinoMed, CNKI, Wanfang and CQVIP) databases, from the dates of the databases' inception to January 2020. The parameters of polysomnography (PSG), actigraphy, or micromovement sensitive mattress/pillow sleep monitoring systems were considered as the primary outcome measures. Revman 5.3 and Stata 16.0 software were used to conduct the meta-analysis. Heterogeneity was examined by using I2 statistics and publication bias was assessed via Egger's test. Results: Eleven studies involving 775 patients met the inclusion criteria. The results of meta-analysis suggested that acupuncture can increase total sleep time [MD = 55.29, 95%CI (29.16, 81.42), p < 0.01], increase sleep efficiency [MD = 8.96, 95%CI (3.97, 13.95), p < 0.01], decrease wake after sleep onset [MD = −49.54, 95%CI (−82.98, −16.09), p < 0.01], and reduce number of awakening times [MD = −6.29, 95%CI (−10.75, −1.82), p < 0.01] compared with either sham-/placebo-acupuncture or waitlist control. Subsequent analysis indicated a superior effect for verum-acupuncture in comparison with sham-/placebo-acupuncture or waitlist-control when the recommended lowest threshold dosage (12 sessions) was met. Despite positive outcomes, most studies reviewed were heterogeneous and at risk of bias due to methodological issues. Conclusions: Despite limited evidence, acupuncture was significantly associated with improvements in several objective sleep parameters (increases in total sleep time and sleep efficiency, and reductions in wake after sleep onset and number of awakening times) as well as subjective sleep quantity and quality in patients with PI. A minimum therapeutic threshold dosage (≥12 sessions) is recommended. Well-designed RCTs using PSG are required to clarify the influence of acupuncture on sleep architecture/structure and to promote better application of acupuncture as a treatment for PI.