BACKGROUND: Although conventional non-pharmacological and pharmacological treatments for insomnia are effective in many people, alternative therapies such as acupuncture are still widely practiced. However, it remains unclear whether the existing evidence is rigorous enough to support its use. OBJECTIVES: To determine the efficacy and safety of acupuncture in people with insomnia. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, PsycINFO, Dissertation Abstracts International, CINAHL, AMED (the Allied and Complementary Medicine Database), TCMLARS (Traditional Chinese Medical Literature Analysis and Retrieval System), National Center for Complementary and Alternative Medicine, the National Institute of Health Clinical Trials Database, the Chinese Acupuncture Trials Register, the Trials Register of the Cochrane Complementary Medicine Field, from inception to 2006, and the sleep bibliography, which is available at www.websciences.org/bibliosleep. We searched reference lists of retrieved articles, and contacted trial authors and experts in the field for information on ongoing/completed trials. SELECTION CRITERIA: Randomised controlled trials evaluating any form of acupuncture involving participants of any age with any type of insomnia were included. Included trials compared acupuncture with placebo or sham or no treatment, or acupuncture plus other treatments compared with the same other treatments. Trials that compared only acupuncture methods or compared acupuncture alone against other treatments alone were excluded, since they did not yield the net effect of acupuncture. DATA COLLECTION AND ANALYSIS: Two review authors independently extracted data and assessed quality according to a set of criteria for risk of selection bias, performance bias, attrition bias and detection bias. Relative risk (RR) and standardised mean difference (SMD) with 95% confidence intervals were used for binary and continuous outcomes respectively. Data were combined in meta-analyses (on an intention-to-treat basis), where more than one trial without significant clinical heterogeneity presented the same outcome. MAIN RESULTS: Seven trials met the inclusion criteria. The studies included 590 participants with insomnia, of whom 56 dropped out. Participant age ranged from 15 to 98 years, and the duration of insomnia varied from 6 months to 19 years. Co-existing medical conditions contributing to insomnia included stroke, end-stage renal disease and pregnancy. Apart from conventional needle acupuncture, different variants of acupuncture such as acupressure, auricular magnetic and seed therapy, and transcutaneous electrical acupoint stimulation (TEAS) were evaluated. Meta-analysis was limited because of considerable heterogeneity between comparison groups and between outcome measures. Based on the findings from individual trials, the review suggested that acupuncture and acupressure may help to improve sleep quality scores when compared to placebo (SMD = -1.08, 95% CI = -1.86 to -0.31, p=0.006) or no treatment (SMD -0.55, 95% CI = -0.89 to -0.21, p=0.002). TEAS also resulted in better sleep quality score in one trial (SMD = -0.74, 95% CI = -1.22 to -0.26, p=0.003). However, the efficacy of acupuncture or its variants was inconsistent between studies for many sleep parameters, such as sleep onset latency, total sleep duration and wake after sleep onset. The combined result from three studies reporting subjective insomnia improvement showed that acupuncture or its variants was not more significantly effective than control (RR = 1.66, 95% CI = 0.68 to -4.03) and significant statistical heterogeneity was observed. Only one study reported an adverse event, with one out of 16 patients (6.3%) withdrawing from acupuncture because of pain. AUTHORS' CONCLUSIONS: The small number of randomised controlled trials, together with the poor methodological quality and significant clinical heterogeneity, means that the current evidence is not sufficiently extensive or rigorous to support the use of any form of acupuncture for the treatment of insomnia. Larger high quality clinical trials employing appropriate randomisation concealment and blinding with longer follow-up are needed to further investigate the efficacy and safety of acupuncture for the treatment of insomnia.