Vagus nerve stimulation (VNS) is an adjunctive treatment for refractory epilepsy. Although widely used, there is still a substantial number of patients with insufficient response. Light, and particularly blue light, can stimulate alertness, attention and cognition through modulation of anatomical targets which are common to the vagal afferent network. This project aims at understanding how exposure to blue enriched light may influence VNS effects in patients with refractory epilepsy by exploring the modulation of a series of biomarkers of VNS action. This could possibly lead to new therapeutic strategies to increase efficacy of VNS.