Effects of elastomer roller stimulation of facial skin on autonomic nervous activity
Suppressed vagal activity is known to be associated with various diseases, e.g., heart diseases  or major depressive disorder . Direct electrical vagus nerve stimulation improves the manifestations of these diseases . In a simpler way, breathing slowly can decrease blood pressure in hypertensive patients by enhancing vagus nerve activity . Therefore, a simple technique for enhancing vagal activity would be useful.
A cooling stimulus on facial skin or a mechanical stimulus that exerts light pressure on the eyeballs lead to a decrease in heart rate via stimulation of the trigeminal nerves. Although these are simple methods that accelerate vagus nerve activity, they can be accompanied by discomfort or pain due to cooling or pressure [4, 5].
Hotta et al.  showed that noninvasive mechanical stimulation with a roller-type tool coated with elastomer resin activates low-threshold mechanoreceptive C fibers and induces autonomic nerve reactions in rats. Meanwhile,...
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
The study protocol was approved by the Ethics Committee of Tokoha University (2017-012H) and has been performed in accordance with the 1964 Declaration of Helsinki and its later amendments.
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