In his book “Bliss Brain”, Mr Dawson claims that when you “relax your tongue on the floor of the mouth, [it] sends a signal to your vagus nerve which wanders all over your body, connecting all the major organ systems. It’s the key signaling component of the parasympathetic nervous system, which governs relaxation” (Church, page 31).
He is right about vagus nerve but wrong about the position of the tongue. He has misread his source.
On page 307, he listed a study by Schmidht, J.E. et al on the “Effects tongue position on mandibular muscle activity and heart rate function” (Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 108(6), 881-888).
What does this study say?
“Results indicated significantly more activity in the temporalis and suprahyoid muscle regions as well as a significant reduction in heart rate variability when THE TONGUE was positioned on the PALATE compared with TONGUE position on the FLOOR of the mouth.” Not on the floor of the mouth!
The authors of this study conclude that “[i]nstructions to place the tongue on the roof of the mouth are not instructions that will promote reduced physiological functioning (i.e., relaxation) but rather promote small, but potentially important increases in overall activity as indexed by muscle tone and cardiac function.”
