Transcutaneous auricular vagus nerve stimulation (taVNS) improves sleep quality in chronic insomnia disorder: A double-blind, randomized, sham-controlled trial.

BACKGROUND: Insomnia is a common sleep disorder that significantly impacts quality of life and health. Conventional treatments such as cognitive-behavioral therapy and pharmacological interventions have limitations, underscoring the need for non-invasive alternatives. Transcutaneous auricular vagus nerve stimulation (taVNS) has emerged as a promising therapy to enhance sleep quality by modulating the autonomic nervous system. OBJECTIVE: This study aimed to evaluate the efficacy and safety of taVNS compared to sham in managing chronic insomnia disorder. METHODS: A randomized, double-blind, sham-controlled trial was conducted with 40 participants diagnosed with chronic insomnia disorder. Participants were randomly assigned to receive taVNS or sham for 30 min daily over six weeks. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI) as the primary outcome. Secondary outcomes included the Insomnia Severity Index (ISI), World Health Organization Quality of Life Brief Version (WHOQOL-BREF), and total sleep time. Adverse events were recorded, and objective sleep measures were obtained using Fitbit wearable devices. RESULTS: In the modified intention-to-treat analysis at 6 weeks, the taVNS group exhibited significantly greater reductions in PSQI scores compared to the sham group (mean change: 4.5 ± 3.55 vs. -1.9 ± 2.15; Cohen's d = -1.21; p = .009). ISI scores also improved more in the taVNS group (-7.6 ± 5.23 vs. -4.25 ± 3.48; Cohen's d = -.75; p = .023). Total sleep time increased significantly in the taVNS group (584 ± 1015 min, vs. -10.8 ± 579 min; Cohen's d = .69; p = .019) and improved quality of life (WHOQOL-BREF: 32.2 ± 40.9 vs. 7.95 ± 33.5; Cohen's d = .65, p = .047). No significant adverse events were reported. CONCLUSIONS: taVNS significantly improved sleep quality, insomnia severity, and overall quality of life compared to sham. These findings establish taVNS as a safe and effective non-invasive therapy for managing insomnia, with potential for broader clinical applications.