A device for facilitating nasal breathing with the mouth closed, including a mouth guard having a maxillary support face and symmetrical two half-arcs on either side of a medial direction (m) and joining one another at a front area of the mouth guard. The mouth guard includes, in its front area an upper anterior edge, wherein it includes a lip protection including an upper part arranged in the extension of the upper anterior edge and extending above the maxillary support face. The upper part including two upper extensions configured so as to form a support area and advantageously to push forward the gingivolabial groove of a user enabling the airway to be increased.
