The tongue position influences the whole body. If the tongue is positioned against the palate, the parasympathetic system will reduce its systemic activity (for example, heartbeats and respiratory rhythm increase), but if it is positioned against the soft palate, the sympathetic system will reduce its activity [1]
1Effects of tongue position on mandibular muscle activity and heart rate function. Schmidt JE, Carlson CR, Usery AR, Quevedo AS. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2009;108:881–888.[PubMed] [Google Scholar]