INTRODUCTION: Primary insomnia (PI) is commonly defined as a state of having disturbed daytime activities due to poor night-time sleep quality. Studies have demonstrated that it is a disorder of 24 h hyperarousal, expressed in terms of physiological, cognitive and cortical activation. Acupuncture is considered to be beneficial to restore the normal sleep-wake cycle. The aim of the trial is to assess the therapeutic effects of acupuncture on sleep quality and hyperarousal state in patients with PI. METHODS AND ANALYSIS: This study is a randomised, patient-assessor-blinded, sham controlled trial. -88 eligible patients with PI will be randomised in a ratio of 1:1 to the intervention group (real acupuncture) and control group (sham acupuncture, super fi cial insertion at irrelevant acupuncture points). Acupuncture intervention will be given to all participants three times a week for 4 weeks, followed up for 8 weeks.The primary outcome measures are the Pittsburgh Sleep Quality Index (PSQI) and Hyperarousal scale (HAS). The secondary outcomes are Fatigue scale-14 (FS-14), polysomnography (PSG), heart rate variability (HRV) and Morning Salivary Cortisol Level (MSCL). Outcomes will be evaluated at baseline, post-treatment period and 8 weeks follow-up. All main analyses will be carried out on the basis of the intention-to-treat principle. ETHICS/DISSEMINATION: This protocol has been approved by the Medical Ethical Committee of Beijing Traditional Chinese Medicine Hospital (Beijing TCM Hospital) on 5 January 2015. The permission number is 2014BL-056-02. The study will present data concerning the clinical effects of treating primary insomnia with acupuncture. The results will help to demonstrate if acupuncture is an effective therapy for improving sleep quality in association with a decreased hyperarousal level as a possible underlying mechanism. The findings from this study will be shared with the healthcare professionals, general public and relevant organisations through publication of manuscripts and conference presentations. TRIAL REGISTRATION NUMBER: ISRCTN16079489; Pre-results.