Clinical Evaluation of the Time-effect Relationship of Auriculoacupuncture at Point Zero on Autonomic Function among Healthy Volunteers: An Exploratory Three-arm Study by Annamalai Dharuman, Deepa Saravanan, Prabu Narasimman, Geethanjali Sankar, Narmatha Murugan, Madhumitha Vellingiri, Abirami Balu