One nerve, two Stories: Low- and high-frequency external trigeminal nerve stimulation (eTNS) shape cortical and autonomic sleep dynamics differently

In recent years, neuromodulation research has gained significant global momentum. Among various peripheral targets, the trigeminal nerve—the largest cranial nerve—has drawn increasing interest due to its high-bandwidth sensory input and robust anatomical connections with key brain regions such as the locus coeruleus, nucleus tractus solitarius, thalamus, and cerebral cortex[1]. These pathways enable trigeminal nerve stimulation to influence widespread cortical and subcortical activity, positioning external trigeminal nerve stimulation (eTNS) as a promising non-invasive approach for conditions including epilepsy, insomnia, brain injury, and cognitive dysfunction[1, 2].