Acupuncture for primary insomnia: Effectiveness, safety, mechanisms and recommendations for clinical practice

This comprehensive review examines the role of acupuncture in the treatment of primary insomnia, a condition affecting approximately 10% of the world's adult population and a growing problem in modern society. Primary insomnia, unlike secondary insomnia, occurs independently of other medical conditions and is caused mainly by general psychophysiologic hyperactivation. The study highlights the limitations of current conventional therapies: although cognitive behavioral therapy for insomnia (CBT-I) is highly effective, its availability is limited by the scarcity of trained therapists, while hypnotics carry risks of tolerance, dependence, and adverse events. Analysis of 12 randomized controlled clinical trials showed that acupuncture demonstrates significant efficacy in improving subjective sleep quality, assessed using standardized scales such as the Pittsburgh Sleep Quality Index (PSQI).

Benefits are maintained over follow-up periods of 1 to 13 weeks, suggesting specific sleep-promoting effects beyond placebo. Objective parameters measured by polysomnography and actigraphy confirmed efficacy, showing reduced sleep latency, increased total sleep time, and improved sleep efficiency. Acupuncture also demonstrated the ability to partially normalize the disordered sleep architecture in primary insomnia, increasing N3 and REM sleep percentages and decreasing N1. The most commonly used acupuncture points were Shenmen (HT-7), Baihui (GV-20), and Sanyinjiao (SP-6), with evidence suggesting that a minimum of 12 sessions is required to optimize results.

In addition to sleep benefits, acupuncture proved effective in improving comorbid symptoms such as depression, anxiety, fatigue, and cognitive impairment, reflecting its holistic approach. Animal studies provided valuable insights into mechanisms of action, including regulation of melatonin and its receptors, modulation of circadian genes, inhibition of the hyperactive hypothalamic-pituitary-adrenal axis, regulation of inflammatory cytokines, modulation of neurotransmitters (GABA, serotonin, norepinephrine), effects on brain-derived neurotrophic factor (BDNF) and its related pathways, regulation of orexin-A neurons, and alteration of the gut microbiota. Acupuncture can be used as primary or adjunctive therapy, showing potential when combined with reduced doses of hypnotics, during medication taper, or in combination with CBT-I to enhance therapeutic effects. In terms of safety, acupuncture has minimal and transient adverse events, mainly mild subcutaneous bruising and pain at the needle insertion site, with a rate below 3.1% and no serious adverse events reported.

Despite the promising results, methodological limitations in some studies, including inadequate sample-size estimation, lack of follow-up periods, and incomplete statistical analyses, weaken the overall quality of evidence. Recommendations include the use of acupuncture as a primary approach followed by combination with lower doses of hypnotics if necessary, use during medication taper to manage withdrawal symptoms, and integration with CBT-I to improve sleep and mitigate daytime drowsiness. This review establishes acupuncture as a promising, natural, and low-risk therapeutic option for individuals with primary insomnia, especially for those who cannot tolerate hypnotics or do not have access to CBT-I, providing a solid basis for its integration into clinical sleep care.