Transcutaneous Auricular Vagus Nerve Stimulation in Insomnia: A Systematic Review and Meta-Analysis

A 2025 systematic review and meta-analysis pooled six studies involving 336 participants with insomnia. It reported improvements in sleep quality and insomnia severity, while the certainty of evidence was rated low to very low.

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IN PLAIN ENGLISH

What this review examined.

The review brought together clinical studies examining transcutaneous auricular vagus nerve stimulation in people with insomnia. The pooled analysis focused on two commonly used outcomes: sleep quality measured with the Pittsburgh Sleep Quality Index (PSQI) and insomnia severity measured with the Insomnia Severity Index (ISI).

The results were statistically significant, but the evidence base was small and the certainty of evidence was limited. The findings therefore need to be read alongside the study methods, stimulation protocols and populations included.

STUDY DESIGN

Study at a glance.

Study type: Systematic review and meta-analysis
Databases searched: PubMed, Embase and CENTRAL
Search period: From database inception through January 2025
Studies screened: 313
Studies included: 6
Total participants: 336
Population: People with insomnia
Primary outcomes: Sleep quality measured with PSQI and insomnia severity measured with ISI

POOLED RESULTS

What the review found.

Lower scores indicate improvement on both the PSQI and ISI scales.

Sleep quality — PSQI

Effect estimate: Mean difference: −3.60
Confidence interval: 95% confidence interval: −4.98 to −2.22
p-value: p < 0.01
Evidence certainty: Low certainty

The pooled analysis reported lower PSQI scores in the taVNS groups, indicating an improvement in measured sleep quality.

Insomnia severity — ISI

Effect estimate: Mean difference: −5.24
Confidence interval: 95% confidence interval: −9.02 to −1.46
p-value: p < 0.01
Evidence certainty: Very low certainty

The pooled analysis reported lower ISI scores in the taVNS groups, indicating an improvement in measured insomnia severity.

Additional sleep outcomes

The included studies also reported improvements across sleep-related measures including sleep latency, duration, efficiency and overall sleep quality.

EVIDENCE AND INTERPRETATION

How to interpret the findings.

Certainty of evidence

The certainty of evidence was rated low for sleep quality and very low for insomnia severity. This limits how confidently the pooled estimates can be interpreted.

Size and variation of the evidence base

Only six studies were included. Stimulation protocols, study methods and participant groups varied, and further standardisation and independent research are needed.

Scope of the finding

The review examined the wider taVNS research field. It did not study the Neuvago device, and its findings cannot automatically be assumed to apply to every taVNS protocol, device or user.

SOURCE DETAILS

Citation and original sources.

de Oliveira HM, Gallo Ruelas M, Viana Diaz CA, Oliveira de Paula G, Fruett da Costa PR, Pilitsis JG. Transcutaneous Auricular Vagus Nerve Stimulation in Insomnia: A Systematic Review and Meta-Analysis. Neuromodulation. 2025;28(8):1332–1340.

DOI: 10.1016/j.neurom.2025.04.001
Open DOI record
PubMed: PMID 40323248
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The original paper remains the primary scientific source.

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