To examine the extent to which research supports the use of acupuncture in treating insomnia, a systematic review was conducted that included not only clinical trials, but also case series in both English and Chinese literature. Thirty studies were included in the review, 93% of which showed positive treatment effects of acupuncture in improving various aspects of sleep. Although acupuncture has been demonstrated to be safe and holds great potential to be an effective treatment modality for insomnia, the evidence is limited by the quality of these studies and mixed results from those with sham (or unreal treatment) controls. Of the thirty studies, twelve were clinical trials with only three double-blinded. Only five used sham controls, and of these, four showed statistically significant differences favoring real treatments; however, none evaluated the adequacy of sham assignment. Three studies used actigraphy or polysomnography as objective outcome measures. The considerable heterogeneity of acupuncture techniques and acupoint selections among all studies made the results difficult to compare and integrate. High-quality randomized clinical trials of acupuncture in treating insomnia, with proper sham and blinding procedures will be required in the future. This review highlights aspects of acupuncture treatments important to guide future research and clinical practice.