Effects of cervical transcutaneous Vagus Nerve Stimulation (ctVNS) on military cognitive performance during sleep deprivation

A 2 × 2 minute stimulation protocol may not be sufficient to elicit beneficial effects on cognitive-and operational military performance. Moreover, correct stimulation intensity may be critical to induce effects on cognitive performance, as stimulation effects may follow an inverted-u dose-response curve. Stimulation intensities in the current study are higher compared to a similar study that reported beneficial effects of ctVNS, which may explain this null finding. Further research is recommended to optimize stimulation protocols and investigate robustness of effects.