Efficacy of transcranial alternating current stimulation for musculoskeletal pain and sleep quality: a systematic review and meta-analysis.
BACKGROUND: Transcranial alternating current stimulation (tACS) is a non-invasive neuromodulation technique, emerging as a potential therapeutic option for musculoskeletal pain management. OBJECTIVE: To comprehensively evaluate the efficacy and safety of tACS for alleviating pain and improving sleep quality in adults with musculoskeletal pain. METHODS: We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs). Seven major databases and other sources were searched from inception until April 2026. Two reviewers independently screened studies, extracted data, and assessed risk of bias. A random-effects model was used to pool standardized mean differences (SMDs). The certainty of evidence was evaluated using the Grading of Recommendation Assessment, Development, and Evaluation framework. RESULTS: Six RCTs involving 232 participants were included. Meta-analysis showed that tACS could significantly reduce pain intensity compared to control (SMD = -0.355, 95% CI: -0.625 to -0.084, p = 0.010, I² = 28.7%). However, no significant improvement was found for sleep quality (SMD = 0.004, 95% CI: -0.310-0.317, p = 0.982, I² = 0.0%). Adverse effects were mild and transient, comparable to sham stimulation. The overall certainty of evidence was rated as low for both pain and sleep quality outcomes. CONCLUSION: Current evidence suggests that tACS may be beneficial for musculoskeletal pain; however, the available evidence remains limited and should be interpreted cautiously. The effect of tACS on sleep quality remains uncertain because of the limited number of available studies. Future well-designed RCTs with standardized outcome measures, condition-specific stimulation protocols, and longer follow-up are required to establish the efficacy and long-term safety of tACS.